Codebook design and structure for advanced wireless communication systems

ABSTRACT

A base station capable of communicating with a user equipment (UE) includes a transceiver configured to transmit downlink signals containing first and second antenna numbers, first and second oversampling factors indicating respective oversampling rates in first and second dimensions for each beam group, first and second quantities of beams indicating respective quantities of beams in the first and second dimensions for each beam group, and first and second beam skip numbers indicating respective differences of leading beam indices of two adjacent beam groups in the first and second dimensions, receive uplink signals containing a plurality of precoding matrix indicators (PMIs) from the UE. Other embodiments including methods and UEs and methods are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION AND CLAIMS OF PRIORITY

This application claims priority under 35 U.S.C. §119(e) to:

-   U.S. Provisional Patent Application No. 62/154,525 filed on Apr. 29,    2015,-   U.S. Provisional Patent Application No. 62/187,585 filed on Jul. 1,    2015,-   U.S. Provisional Patent Application No. 62/194,404 filed on Jul. 20,    2015,-   U.S. Provisional Patent Application No. 62/198,408 filed on Jul. 29,    2015,-   U.S. Provisional Patent Application No. 62/199,637 filed on Jul. 31,    2015,-   U.S. Provisional Patent Application No. 62/201,926 filed on Aug. 6,    2015,-   U.S. Provisional Patent Application No. 62/213,988 filed on Sep. 3,    2015,-   U.S. Provisional Patent Application No. 62/216,610 filed on Sep. 10,    2015,-   U.S. Provisional Patent Application No. 62/222,102 filed on Sep. 22,    2015,-   U.S. Provisional Patent Application No. 62/239,587 filed on Oct. 9,    2015, and-   U.S. Provisional Patent Application No. 62/241,512 filed on Oct. 14,    2015.

The above-identified provisional patent applications are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to a codebook design andstructure associated with a two dimensional transmit antenna array. Suchtwo dimensional arrays are associated with a type ofmultiple-input-multiple-output (MIMO) system often termed“full-dimension” MIMO (FD-MIMO).

BACKGROUND

Wireless communication has been one of the most successful innovationsin modern history. Recently, the number of subscribers to wirelesscommunication services exceeded five billion and continues to growquickly. The demand of wireless data traffic is rapidly increasing dueto the growing popularity among consumers and businesses of smart phonesand other mobile data devices, such as tablets, “note pad” computers,net books, eBook readers, and machine type of devices. In order to meetthe high growth in mobile data traffic and support new applications anddeployments, improvements in radio interface efficiency and coverage isof paramount importance.

SUMMARY

In a first embodiment, a user equipment (UE) capable of communicatingwith a base station includes a transceiver configured to receivedownlink signals indicating precoder codebook parameters, the downlinksignal including first and second quantities of antenna ports indicatingrespective quantities of antenna ports in first and second dimensions,first and second oversampling factors indicating respective oversamplingfactors for DFT beams in the first and second dimensions, either atleast one beam group configuration among a plurality of beam groupconfigurations or first and second quantities of beams indicatingrespective quantities of beams in the first and second dimensionsforming a beam group, and first and second beam skip numbers indicatingrespective differences of leading beam indices of two adjacent beamgroups in the first and second dimensions, and a controller configuredto determine a precoder, using the received precoder codebookconfiguration, determine a plurality of precoding matrix indicators(PMIs) based on the received downlink signals, and cause the transceiverto transmit uplink signals containing the plurality of PMIs to the basestation.

In a second embodiment, a base station capable of communicating with auser equipment (UE) includes a transmitter configured to transmitdownlink signals indicating precoder codebook parameters including firstand second quantities of antenna ports indicating respective quantitiesof antenna ports in the first and second dimensions, first and secondoversampling factors indicating respective oversampling factors for DFTbeams in the first and second dimension, either at least one beam groupconfiguration among a plurality of beam group configurations or firstand second quantities of beams indicating respective quantities of beamsin the first and second dimensions forming a beam group, and first andsecond beam skip numbers indicating respective differences of leadingbeam indices of two adjacent beam groups in the first and seconddimensions, and a receiver configured to receive uplink signalscontaining a plurality of precoding matrix indicators (PMIs) from theUE.

In a third embodiment, a method of operating a base station capable ofcommunicating with a user equipment (UE) includes transmitting downlinksignals indicating precoder codebook parameters, the downlink signalincluding first and second quantities of antenna ports indicatingrespective quantities of antenna ports in the first and seconddimensions, first and second oversampling factors indicating respectiveoversampling factors for DFT beams in the first and second dimensions,either at least one beam group configuration among a plurality of beamgroup configurations or first and second quantities of beams indicatingrespective quantities of beams in the first and second dimensionsforming a beam group, and first and second beam skip numbers indicatingrespective differences of leading beam indices of two adjacent beamgroups in the first and second dimensions, receiving uplink signalscontaining a plurality of precoding matrix indicators (PMIs) from theUE.

In a fourth embodiment, a method for user equipment (UE) capable ofcommunicating with a base station includes receiving downlink signalscontaining a precoder configuration set comprising first and secondantenna numbers, first and second oversampling factors indicatingrespective oversampling rates in first and second dimensions for eachbeam group, first and second quantities of beams indicating respectivequantities of beams in the first and second dimensions for each beamgroup, and first and second beam skip numbers indicating respectivedifferences of leading beam indices of two adjacent beam groups in thefirst and second dimensions, and determining a precoder according to thereceived precoder configuration, determining a plurality of precodingmatrix indicators (PMIs) based on the received downlink signals, andtransmitting uplink signals containing the plurality of PMIs to the basestation.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example wireless network according to thisdisclosure;

FIGS. 2A and 2B illustrate example wireless transmit and receive pathsaccording to this disclosure;

FIG. 3A illustrates an example user equipment according to thisdisclosure;

FIG. 3B illustrates an example enhanced NodeB (eNB) according to thisdisclosure;

FIG. 4 illustrates logical port to antenna port mapping 400 that may beemployed within the wireless communication system according to someembodiments of the current disclosure;

FIGS. 5A to 5D illustrate antenna configurations and antenna numberingsaccording to some embodiments of the present disclosure;

FIG. 6 illustrates a precoding weight application to antennaconfigurations of FIGS. 5A to 5D for Numbering scheme 1;

FIG. 7 illustrates a 4×4 dual-polarized antenna array 700 with antennaport (AP) indexing 1;

FIG. 8 is a 4×4 dual-polarized antenna array 800 with antenna portindexing (AP) indexing 2;

FIG. 9 illustrates another numbering of TX antenna elements 900 (orTXRU) according to embodiments of the present disclosure;

FIG. 10 illustrates a beam grouping scheme corresponding to Scheme 1 inTABLE 1 according to embodiment of the present disclosure;

FIG. 11 illustrates a beam grouping scheme corresponding to Scheme 2 inTABLE 1 according to the embodiments of the present disclosure;

FIG. 12 illustrates a beam grouping scheme 1200 corresponding to Scheme3 in TABLE 1 according to embodiments of the present disclosure;

FIG. 13 illustrates a new codebook construction 1300 according toembodiments of the present disclosure;

FIG. 14 illustrates another new codebook construction according toembodiments of the present disclosure;

FIG. 15 illustrates a new codebook construction for P=32 antenna portsaccording to embodiments of the present disclosure;

FIG. 16 shows example beam patterns according to embodiments of thepresent disclosure;

FIG. 17 illustrates an alternate codebook construction in which twodifferent vertical beams may be applied for the two polarizationsaccording to the present disclosure;

FIG. 18 illustrates PUCCH mode 1-1 submode 1 according to embodiments ofthe present disclosure;

FIG. 19 illustrates an example UE elevation angle distribution incellular wireless systems, in urban macro (UMa) and urban micro (UMi)cases;

FIGS. 20 to 22 illustrate three examples of PUCCH mode 1-1 submode 1according to embodiments of the present disclosure;

FIG. 23 illustrates an example of PUCCH mode 1-1 submode x according toembodiments of the present disclosure;

FIGS. 24 to 26 illustrates respective beam grouping schemes 1, 2 and 3according to embodiments of the present disclosure;

FIG. 27 illustrates a master codebook with example beam groups for N1=4and N2=4 according to embodiments of the present disclosure;

FIG. 28 illustrates the subset restriction on rank-1 i1 according toembodiments of the present disclosure;

FIG. 29 illustrates the example beam groups in the master codebook aftersubset restriction according to the present disclosure;

FIG. 30 illustrates the subset restriction 300 on rank-1 i2 according tothe embodiments of the present disclosure;

FIG. 31 illustrates a flowchart 3100 for UE operation for configuringparametrized codebook 3100 according to embodiments of the presentdisclosure;

FIG. 32 illustrates a flowchart of the overall eNB and UE operationaccording to the parameterized codebook according to the presentdisclosure;

FIG. 33 illustrates an example beam group type in which beams areadjacent in both dimensions according to the present disclosure;

FIGS. 34A and 34B illustrate another example beam group types in which abeam group consists of orthogonal beam pairs in the first (horizontal)dimension, and adjacent beams in the second (vertical) dimension;

FIG. 35 illustrates alternative rank-1 beam grouping schemes accordingto some embodiments of the present disclosure;

FIG. 36 illustrate a beam combination to construct rank-2 mastercodebook according to some embodiments of the present disclosure;

FIG. 37 illustrates rank-2 beam grouping schemes for rank-2 i2 accordingto some embodiments of the present disclosure;

FIG. 38 illustrates a beam combination to construct rank-3 and rank-4master codebooks according to some embodiments of the presentdisclosure;

FIG. 39 illustrates grouping schemes for rank-3 and rank-4 i2 accordingto some embodiments of the present disclosure;

FIG. 40 illustrates a beam combination to construct rank 5-8 beamcombination master codebooks according to some embodiments of thepresent disclosure;

FIG. 41 illustrates grouping schemes for rank 5-8 i2 according to someembodiments of the present disclosure;

FIG. 42 illustrate a beam combination to construct a master codebook forrank-2 beam combinations according to embodiments of the presentdisclosure;

FIG. 43 illustrates rank-2 beam grouping schemes according to someembodiments of the present disclosure;

FIG. 44 illustrates beam grouping schemes for rank-3 and rank-4 i2according to the present disclosure;

FIG. 45 illustrates a beam combination to construct ranks 5-8 mastercodebooks according to some embodiments of the present disclosure;

FIG. 46 illustrates beam grouping schemes for ranks 5-8 i2 indicesaccording to the embodiments of the present disclosure;

FIG. 47 illustrates beam grouping scheme or codebook subset selection onrank-2 i2 indices in terms of parameters L1 and L2, according to theembodiments of the present disclosure;

FIG. 48 illustrates rank 3 and rank 4 beam grouping schemes according toembodiments of the present disclosure;

FIG. 49 illustrates ranks 5 to 8 beam grouping schemes according to thepresent disclosure;

FIG. 50 illustrates the master rank-2 codebook designed according toDesign 1 according to the present disclosure;

FIG. 51 illustrates the master rank-2 codebook designed according toDesign 2 according to embodiments of the present disclosure;

FIG. 52 illustrates beam grouping options for Config 1, Config 2, Config3, and Config 4 according to the present disclosure; and

FIG. 53 illustrates rank 2 beam pairs based on nested property with rank1 beam according to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1 through 53, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged wireless communication system.

The following documents and standards descriptions are herebyincorporated by reference into the present disclosure as if fully setforth herein: (1) 3rd generation partnership project (3GPP) TS 36.211,“E-UTRA, Physical channels and modulation”, Release-12; (2) 3GPP TS36.212, “E-UTRA, Multiplexing and channel coding”, Release-12; and (3)3GPP TS 36.213, “E-UTRA, Physical layer procedures”, Release-12.

FIG. 1 illustrates an example wireless network 100 according to thisdisclosure. The embodiment of the wireless network 100 shown in FIG. 1is for illustration only. Other embodiments of the wireless network 100could be used without departing from the scope of this disclosure.

The wireless network 100 includes an eNodeB (eNB) 101, an eNB 102, andan eNB 103. The eNB 101 communicates with the eNB 102 and the eNB 103.The eNB 101 also communicates with at least one Internet Protocol (IP)network 130, such as the Internet, a proprietary IP network, or otherdata network.

Depending on the network type, other well-known terms may be usedinstead of “eNodeB” or “eNB,” such as “base station” or “access point.”For the sake of convenience, the terms “eNodeB” and “eNB” are used inthis patent document to refer to network infrastructure components thatprovide wireless access to remote terminals. Also, depending on thenetwork type, other well-known terms may be used instead of “userequipment” or “UE,” such as “mobile station,” “subscriber station,”“remote terminal,” “wireless terminal,” or “user device.” For the sakeof convenience, the terms “user equipment” and “UE” are used in thispatent document to refer to remote wireless equipment that wirelesslyaccesses an eNB, whether the UE is a mobile device (such as a mobiletelephone or smartphone) or is normally considered a stationary device(such as a desktop computer or vending machine).

The eNB 102 provides wireless broadband access to the network 130 for afirst plurality of user equipments (UEs) within a coverage area 120 ofthe eNB 102. The first plurality of UEs includes a UE 111, which may belocated in a small business (SB); a UE 112, which may be located in anenterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); aUE 114, which may be located in a first residence (R); a UE 115, whichmay be located in a second residence (R); and a UE 116, which may be amobile device (M) like a cell phone, a wireless laptop, a wireless PDA,or the like. The eNB 103 provides wireless broadband access to thenetwork 130 for a second plurality of UEs within a coverage area 125 ofthe eNB 103. The second plurality of UEs includes the UE 115 and the UE116. In some embodiments, one or more of the eNBs 101-103 maycommunicate with each other and with the UEs 111-116 using 5G, long-termevolution (LTE), LTE-A, WiMAX, or other advanced wireless communicationtechniques.

Dotted lines show the approximate extents of the coverage areas 120 and125, which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with eNBs, such as the coverage areas 120and 125, may have other shapes, including irregular shapes, dependingupon the configuration of the eNBs and variations in the radioenvironment associated with natural and man-made obstructions.

As described in more detail below, one or more of BS 101, BS 102 and BS103 include 2D antenna arrays as described in embodiments of the presentdisclosure. In some embodiments, one or more of BS 101, BS 102 and BS103 support the codebook design and structure for systems having 2Dantenna arrays.

Although FIG. 1 illustrates one example of a wireless network 100,various changes may be made to FIG. 1. For example, the wireless network100 could include any number of eNBs and any number of UEs in anysuitable arrangement. Also, the eNB 101 could communicate directly withany number of UEs and provide those UEs with wireless broadband accessto the network 130. Similarly, each eNB 102-103 could communicatedirectly with the network 130 and provide UEs with direct wirelessbroadband access to the network 130. Further, the eNB 101, 102, and/or103 could provide access to other or additional external networks, suchas external telephone networks or other types of data networks.

FIGS. 2A and 2B illustrate example wireless transmit and receive pathsaccording to this disclosure. In the following description, a transmitpath 200 may be described as being implemented in an eNB (such as eNB102), while a receive path 250 may be described as being implemented ina UE (such as UE 116). However, it will be understood that the receivepath 250 could be implemented in an eNB and that the transmit path 200could be implemented in a UE. In some embodiments, the receive path 250is configured to support the codebook design and structure for systemshaving 2D antenna arrays as described in embodiments of the presentdisclosure.

The transmit path 200 includes a channel coding and modulation block205, a serial-to-parallel (S-to-P) block 210, a size N Inverse FastFourier Transform (IFFT) block 215, a parallel-to-serial (P-to-S) block220, an add cyclic prefix block 225, and an up-converter (UC) 230. Thereceive path 250 includes a down-converter (DC) 255, a remove cyclicprefix block 260, a serial-to-parallel (S-to-P) block 265, a size N FastFourier Transform (FFT) block 270, a parallel-to-serial (P-to-S) block275, and a channel decoding and demodulation block 280.

In the transmit path 200, the channel coding and modulation block 205receives a set of information bits, applies coding (such as alow-density parity check (LDPC) coding), and modulates the input bits(such as with Quadrature Phase Shift Keying (QPSK) or QuadratureAmplitude Modulation (QAM)) to generate a sequence of frequency-domainmodulation symbols. The serial-to-parallel block 210 converts (such asde-multiplexes) the serial modulated symbols to parallel data in orderto generate N parallel symbol streams, where N is the IFFT/FFT size usedin the eNB 102 and the UE 116. The size N IFFT block 215 performs anIFFT operation on the N parallel symbol streams to generate time-domainoutput signals. The parallel-to-serial block 220 converts (such asmultiplexes) the parallel time-domain output symbols from the size NIFFT block 215 in order to generate a serial time-domain signal. The addcyclic prefix block 225 inserts a cyclic prefix to the time-domainsignal. The up-converter 230 modulates (such as up-converts) the outputof the add cyclic prefix block 225 to an RF frequency for transmissionvia a wireless channel. The signal may also be filtered at basebandbefore conversion to the RF frequency.

A transmitted RF signal from the eNB 102 arrives at the UE 116 afterpassing through the wireless channel, and reverse operations to those atthe eNB 102 are performed at the UE 116. The down-converter 255down-converts the received signal to a baseband frequency, and theremove cyclic prefix block 260 removes the cyclic prefix to generate aserial time-domain baseband signal. The serial-to-parallel block 265converts the time-domain baseband signal to parallel time domainsignals. The size N FFT block 270 performs an FFT algorithm to generateN parallel frequency-domain signals. The parallel-to-serial block 275converts the parallel frequency-domain signals to a sequence ofmodulated data symbols. The channel decoding and demodulation block 280demodulates and decodes the modulated symbols to recover the originalinput data stream.

Each of the eNBs 101-103 may implement a transmit path 200 that isanalogous to transmitting in the downlink to UEs 111-116 and mayimplement a receive path 250 that is analogous to receiving in theuplink from UEs 111-116. Similarly, each of UEs 111-116 may implement atransmit path 200 for transmitting in the uplink to eNBs 101-103 and mayimplement a receive path 250 for receiving in the downlink from eNBs101-103.

Each of the components in FIGS. 2A and 2B can be implemented using onlyhardware or using a combination of hardware and software/firmware. As aparticular example, at least some of the components in FIGS. 2A and 2Bmay be implemented in software, while other components may beimplemented by configurable hardware or a mixture of software andconfigurable hardware. For instance, the FFT block 270 and the IFFTblock 215 may be implemented as configurable software algorithms, wherethe value of size N may be modified according to the implementation.

Furthermore, although described as using FFT and IFFT, this is by way ofillustration only and should not be construed to limit the scope of thisdisclosure. Other types of transforms, such as Discrete FourierTransform (DFT) and Inverse Discrete Fourier Transform (IDFT) functions,could be used. It will be appreciated that the value of the variable Nmay be any integer number (such as 1, 2, 3, 4, or the like) for DFT andIDFT functions, while the value of the variable N may be any integernumber that is a power of two (such as 1, 2, 4, 8, 16, or the like) forFFT and IFFT functions.

Although FIGS. 2A and 2B illustrate examples of wireless transmit andreceive paths, various changes may be made to FIGS. 2A and 2B. Forexample, various components in FIGS. 2A and 2B could be combined,further subdivided, or omitted and additional components could be addedaccording to particular needs. Also, FIGS. 2A and 2B are meant toillustrate examples of the types of transmit and receive paths thatcould be used in a wireless network. Any other suitable architecturescould be used to support wireless communications in a wireless network.

FIG. 3A illustrates an example UE 116 according to this disclosure. Theembodiment of the UE 116 illustrated in FIG. 3A is for illustrationonly, and the UEs 111-115 of FIG. 1 could have the same or similarconfiguration. However, UEs come in a wide variety of configurations,and FIG. 3A does not limit the scope of this disclosure to anyparticular implementation of a UE.

The UE 116 includes an antenna 305, a radio frequency (RF) transceiver310, transmit (TX) processing circuitry 315, a microphone 320, andreceive (RX) processing circuitry 325. The UE 116 also includes aspeaker 330, a main processor 340, an input/output (I/O) interface (IF)345, a keypad 350, a display 355, and a memory 360. The memory 360includes a basic operating system (OS) program 361 and one or moreapplications 362.

The RF transceiver 310 receives, from the antenna 305, an incoming RFsignal transmitted by an eNB of the network 100. The RF transceiver 310down-converts the incoming RF signal to generate an intermediatefrequency (IF) or baseband signal. The IF or baseband signal is sent tothe RX processing circuitry 325, which generates a processed basebandsignal by filtering, decoding, and/or digitizing the baseband or IFsignal. The RX processing circuitry 325 transmits the processed basebandsignal to the speaker 330 (such as for voice data) or to the mainprocessor 340 for further processing (such as for web browsing data).

The TX processing circuitry 315 receives analog or digital voice datafrom the microphone 320 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the main processor340. The TX processing circuitry 315 encodes, multiplexes, and/ordigitizes the outgoing baseband data to generate a processed baseband orIF signal. The RF transceiver 310 receives the outgoing processedbaseband or IF signal from the TX processing circuitry 315 andup-converts the baseband or IF signal to an RF signal that istransmitted via the antenna 305.

The main processor 340 can include one or more processors or otherprocessing devices and execute the basic OS program 361 stored in thememory 360 in order to control the overall operation of the UE 116. Forexample, the main processor 340 could control the reception of forwardchannel signals and the transmission of reverse channel signals by theRF transceiver 310, the RX processing circuitry 325, and the TXprocessing circuitry 315 in accordance with well-known principles. Insome embodiments, the main processor 340 includes at least onemicroprocessor or microcontroller.

The main processor 340 is also capable of executing other processes andprograms resident in the memory 360, such as operations for channelquality measurement and reporting for systems having 2D antenna arraysas described in embodiments of the present disclosure as described inembodiments of the present disclosure. The main processor 340 can movedata into or out of the memory 360 as required by an executing process.In some embodiments, the main processor 340 is configured to execute theapplications 362 based on the OS program 361 or in response to signalsreceived from eNBs or an operator. The main processor 340 is alsocoupled to the I/O interface 345, which provides the UE 116 with theability to connect to other devices such as laptop computers andhandheld computers. The I/O interface 345 is the communication pathbetween these accessories and the main controller 340.

The main processor 340 is also coupled to the keypad 350 and the displayunit 355. The operator of the UE 116 can use the keypad 350 to enterdata into the UE 116. The display 355 may be a liquid crystal display orother display capable of rendering text and/or at least limitedgraphics, such as from web sites.

The memory 360 is coupled to the main processor 340. Part of the memory360 could include a random access memory (RAM), and another part of thememory 360 could include a Flash memory or other read-only memory (ROM).

Although FIG. 3A illustrates one example of UE 116, various changes maybe made to FIG. 3A. For example, various components in FIG. 3A could becombined, further subdivided, or omitted and additional components couldbe added according to particular needs. As a particular example, themain processor 340 could be divided into multiple processors, such asone or more central processing units (CPUs) and one or more graphicsprocessing units (GPUs). Also, while FIG. 3A illustrates the UE 116configured as a mobile telephone or smartphone, UEs could be configuredto operate as other types of mobile or stationary devices.

FIG. 3B illustrates an example eNB 102 according to this disclosure. Theembodiment of the eNB 102 shown in FIG. 3B is for illustration only, andother eNBs of FIG. 1 could have the same or similar configuration.However, eNBs come in a wide variety of configurations, and FIG. 3B doesnot limit the scope of this disclosure to any particular implementationof an eNB. It is noted that eNB 101 and eNB 103 can include the same orsimilar structure as eNB 102.

As shown in FIG. 3B, the eNB 102 includes multiple antennas 370 a-370 n,multiple RF transceivers 372 a-372 n, transmit (TX) processing circuitry374, and receive (RX) processing circuitry 376. In certain embodiments,one or more of the multiple antennas 370 a-370 n include 2D antennaarrays. The eNB 102 also includes a controller/processor 378, a memory380, and a backhaul or network interface 382.

The RF transceivers 372 a-372 n receive, from the antennas 370 a-370 n,incoming RF signals, such as signals transmitted by UEs or other eNBs.The RF transceivers 372 a-372 n down-convert the incoming RF signals togenerate IF or baseband signals. The IF or baseband signals are sent tothe RX processing circuitry 376, which generates processed basebandsignals by filtering, decoding, and/or digitizing the baseband or IFsignals. The RX processing circuitry 376 transmits the processedbaseband signals to the controller/processor 378 for further processing.

The TX processing circuitry 374 receives analog or digital data (such asvoice data, web data, e-mail, or interactive video game data) from thecontroller/processor 378. The TX processing circuitry 374 encodes,multiplexes, and/or digitizes the outgoing baseband data to generateprocessed baseband or IF signals. The RF transceivers 372 a-372 nreceive the outgoing processed baseband or IF signals from the TXprocessing circuitry 374 and up-converts the baseband or IF signals toRF signals that are transmitted via the antennas 370 a-370 n.

The controller/processor 378 can include one or more processors or otherprocessing devices that control the overall operation of the eNB 102.For example, the controller/processor 378 could control the reception offorward channel signals and the transmission of reverse channel signalsby the RF transceivers 372 a-372 n, the RX processing circuitry 376, andthe TX processing circuitry 324 in accordance with well-knownprinciples. The controller/processor 378 could support additionalfunctions as well, such as more advanced wireless communicationfunctions. For instance, the controller/processor 378 can perform theblind interference sensing (BIS) process, such as performed by a BISalgorithm, and decodes the received signal subtracted by the interferingsignals. Any of a wide variety of other functions could be supported inthe eNB 102 by the controller/processor 378. In some embodiments, thecontroller/processor 378 includes at least one microprocessor ormicrocontroller.

The controller/processor 378 is also capable of executing programs andother processes resident in the memory 380, such as a basic OS. Thecontroller/processor 378 is also capable of supporting channel qualitymeasurement and reporting for systems having 2D antenna arrays asdescribed in embodiments of the present disclosure. In some embodiments,the controller/processor 378 supports communications between entities,such as web RTC. The controller/processor 378 can move data into or outof the memory 380 as required by an executing process.

The controller/processor 378 is also coupled to the backhaul or networkinterface 335. The backhaul or network interface 382 allows the eNB 102to communicate with other devices or systems over a backhaul connectionor over a network. The interface 382 could support communications overany suitable wired or wireless connection(s). For example, when the eNB102 is implemented as part of a cellular communication system (such asone supporting 5G, LTE, or LTE-A), the interface 382 could allow the eNB102 to communicate with other eNBs over a wired or wireless backhaulconnection. When the eNB 102 is implemented as an access point, theinterface 382 could allow the eNB 102 to communicate over a wired orwireless local area network or over a wired or wireless connection to alarger network (such as the Internet). The interface 382 includes anysuitable structure supporting communications over a wired or wirelessconnection, such as an Ethernet or RF transceiver.

The memory 380 is coupled to the controller/processor 325. Part of thememory 330 could include a RAM, and another part of the memory 380 couldinclude a Flash memory or other ROM. In certain embodiments, a pluralityof instructions, such as a BIS algorithm is stored in memory. Theplurality of instructions are configured to cause thecontroller/processor 378 to perform the BIS process and to decode areceived signal after subtracting out at least one interfering signaldetermined by the BIS algorithm.

As described in more detail below, the transmit and receive paths of theeNB 102 (implemented using the RF transceivers 372 a-372 n, TXprocessing circuitry 374, and/or RX processing circuitry 376) supportcommunication with aggregation of FDD cells and TDD cells.

Although FIG. 3B illustrates one example of an eNB 102, various changesmay be made to FIG. 3B. For example, the eNB 102 could include anynumber of each component shown in FIG. 3. As a particular example, anaccess point could include a number of interfaces 382, and thecontroller/processor 378 could support routing functions to route databetween different network addresses. As another particular example,while shown as including a single instance of TX processing circuitry374 and a single instance of RX processing circuitry 376, the eNB 102could include multiple instances of each (such as one per RFtransceiver).

Logical Port to Antenna Port Mapping

FIG. 4 illustrates logical port to antenna port mapping 400 that may beemployed within the wireless communication system according to someembodiments of the current disclosure. The embodiment of the portmapping illustrated in FIG. 4 is for illustration only. However, portmappings come in a wide variety of configurations, and FIG. 4 does notlimit the scope of this disclosure to any particular implementation of aport mapping.

FIG. 4 illustrates logical port to antenna port mapping, according tosome embodiments of the current disclosure. In the figure, Tx signals oneach logical port is fed into an antenna virtualization matrix (e.g., ofa size M×1), output signals of which are fed into a set of M physicalantenna ports. In some embodiments, M corresponds to a total number orquantity of antenna elements on a substantially vertical axis. In someembodiments, M corresponds to a ratio of a total number or quantity ofantenna elements to S, on a substantially vertical axis, wherein M and Sare chosen to be a positive integer.

Antenna Configurations and Antenna Numbering

FIGS. 5A to 5D illustrate antenna configurations and antenna numberingsaccording to one embodiments of the present disclosure. The embodimentsshown in FIGS. 5A to 5D are for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

In all the four antenna configurations of FIGS. 5A to 5D, a cross pol(or X-pol) antenna array is considered, in which a pair of antennaelements in a same physical location are polarized in two distinctangles, e.g., +45 degrees and −45 degrees.

FIGS. 5A and 5B are antenna configurations with 16 CSI-RS ports,comprising 8 pairs of x-pol antenna elements placed in a 2D antennapanel. The 8 pairs can be placed in 2×4 (FIG. 5A) or 4×2 manner (FIG.5B) on horizontal and vertical dimensions.

FIGS. 5C and 5D are antenna configurations with 12 CSI-RS ports,comprising 6 pairs of x-pol antenna elements placed in a 2D antennapanel. The 6 pairs can be placed in 2×3 (FIG. 5C) or 3×2 manner (FIG.5D) on horizontal and vertical dimensions.

Antenna Number Assignment

In FIGS. 5A to 5D, antennas are indexed with integer numbers, 0, 1, . .. , 15 for 16-port configurations (FIGS. 5A and 5B), and 0, . . . , 11for 12-port configurations (FIGS. 5C and 5D).

In wide arrays (such as 12-port config A and 16-port config A), antennanumbers are assigned as follows. Consecutive numbers are assigned forall the antenna elements for a first polarization, and proceed to asecond polarization. And, for a given polarization, Numbering scheme 1:consecutive numbers are assigned for a first row with progressing oneedge to another edge, and proceed to a second row; and Numbering scheme2: consecutive numbers are assigned for a first column with progressingone edge to another edge, and proceed to a second column.

For example, in FIG. 5A, antenna numbers 0-7 are assigned for a firstpolarization, and 8-15 are assigned for a second polarization; andantenna numbers 0-3 are assigned for a first row and 4-7 are assignedfor a second row.

Antenna numbers in tall arrays (such as 12-port config B and 16-portconfig B) are obtained by simply rotating the wide antenna arrays (suchas 12-port config A and 16-port config A) by 90 degrees.

PMI Feedback Precoder Generation according to the Antenna Numbering

In some embodiments, when a UE is configure with 12 or 16 port CSI-RSfor a CSI-RS resource, the UE is configured to report a PMI feedbackprecoder according to the antenna numbers in FIGS. 5A to 5D. A rank-1precoder, W_(m,n,p), which is an N_(CSIRS)x1 vector, to be reported bythe UE has the following form:

${W_{m,n,p} = {\begin{bmatrix}w_{0} & w_{1} & \ldots & w_{N_{CSIRS} - 1}\end{bmatrix}^{t} = {\frac{1}{\sqrt{N_{CSIRS}}}\begin{bmatrix}{v_{m} \otimes u_{n}} \\{\phi_{p}\left( {v_{m^{\prime}} \otimes u_{n^{~\prime}}} \right)}\end{bmatrix}}}},$

wherein:

-   -   N_(CSIRS)=number of configured CSI-RS ports in the CSI-RS        resource, e.g., 12, 16, etc;    -   u_(n) is a N×1 oversampled DFT vector for a second dimension,        whose oversampling factor is S_(N);    -   v_(m) is a M×1 oversampled DFT vector for a first dimension,        whose oversampling factor is S_(M);    -   The dimension assignment can be done with N≧M according to        numbering scheme 1 in FIGS. 4A to 4D, with (N,M) ∈ {(4,2),        (4,3), (2,2)}; alternatively, the dimension assignment can be        done with N≦M with swapping the role of columns and rows, with        (N,M) ∈ {(2,4), (3,4), (2,2)} according to numbering scheme 2 in        FIGS. 4A to 4C; and    -   φ_(p) is a co-phase, e.g., in a form of

$^{\frac{2\pi \; p}{4}},$

p=0,1,2,3.

Here, example set of oversampling factors that can be configured forS_(N) and S_(M) are {2,4,8}; and m, m′ ∈ {0,1, . . . , S_(M)M}, and n,n′ ∈ {0,1, . . . , S_(N)N}. In a special case, m=m′ and n=n′.

FIG. 6 illustrates a precoding weight application to antennaconfigurations of FIGS. 5A to 5D for numbering scheme 1.

When any of 16-port config A and B for Numbering scheme 1 is used at theeNB with configuring N_(CSIRS)=16 to the UE, a submatrix v_(m)

u_(n) of W_(m,n,p) corresponds to a precoder applied on 8 co-polelements, whose antenna numbers are 0 through 7. Given the antennaconfiguration, M=2 and N=4 should be configured for v_(m) and u_(n).

If 16-port config A is used, u_(n) is a 4×1 vector representing ahorizontal DFT beam and v_(m) is a 2×1 vector representing a verticalDFT beam. If 16-port config B is used, u_(n) is a 4×1 vectorrepresenting a vertical DFT beam and v_(m) is a 2×1 vector representinga horizontal DFT beam.

With 12 or 16-port configurations, v_(m) can be written as

$v_{m} = {\begin{bmatrix}1 & ^{j\frac{2\pi \; m}{M^{\prime}}}\end{bmatrix}^{t} = {\begin{bmatrix}1 & ^{j\frac{2\pi \; m}{{MS}_{M}}}\end{bmatrix}^{t}.}}$

With 16-port configurations, u_(n) can be written as:

$\begin{matrix}{u_{n} = \begin{bmatrix}1 & ^{j\frac{2\; \pi \; n}{N^{\prime}}} & ^{j\frac{4\; \pi \; m}{N^{\prime}}} & ^{j\frac{6\; \pi \; m}{N^{\prime}}}\end{bmatrix}^{t}} \\{= {\begin{bmatrix}1 & ^{j\frac{2\pi \; n}{{NS}_{N}}} & ^{j\frac{4\; \pi \; m}{{NS}_{N}}} & ^{j\frac{6\pi \; m}{{NS}_{N}}}\end{bmatrix}^{t}.}}\end{matrix}$

With 12-port configurations, u_(n) can be written as:

$\begin{matrix}{u_{n} = \begin{bmatrix}1 & ^{j\frac{2\; \pi \; n}{N^{\prime}}} & ^{j\frac{4\; \pi \; m}{N^{\prime}}}\end{bmatrix}^{t}} \\{= {\begin{bmatrix}1 & ^{j\frac{2\pi \; n}{{NS}_{N}}} & ^{j\frac{4\pi \; m}{{NS}_{N}}}\end{bmatrix}^{t}.}}\end{matrix}$

Precoding weights to be applied to antenna port numbers 0 through 3 areu_(n), and the precoding weights to be applied to antenna ports 4through 7 are

$u_{n}^{j\frac{2\; \pi \; m}{{MS}_{M}}}$

with an appropriate power normalization factor. Similarly, precodingweights to be applied to antenna port numbers 8 through 11 are u_(n′),and the precoding weights to be applied to antenna ports 12 through 15are

$u_{n^{\prime}}^{j\frac{2\; \pi \; m^{\prime}}{{MS}_{M}}}$

with an appropriate power normalization factor. This method of precodingweight application for Numbering scheme 1 is illustrated in FIGS. 5A to5D. Note that the method is also applicable to Numbering scheme 2.

FIG. 7 illustrates a 4×4 dual-polarized antenna array 700 with antennaport (AP) indexing 1 and FIG. 8 is the same 4×4 dual-polarized antennaarray 800 with antenna port indexing (AP) indexing 2.

In certain embodiments, each labelled antenna element is logicallymapped onto a single antenna port. In general, one antenna port cancorrespond to multiple antenna elements (physical antennas) combined viaa virtualization. This 4×4 dual polarized array can then be viewed as16×2=32-element array of elements. The vertical dimension (consisting of4 rows) facilitates elevation beamforming in addition to the azimuthalbeamforming across the horizontal dimension (consisting of 4 columns ofdual polarized antennas). MIMO precoding in Rel.12 LTE standardization(per TS36.211 sections 6.3.4.2 and 6.3.4.4; and TS36.213 section 7.2.4)was largely designed to offer a precoding gain for one-dimensionalantenna array. While fixed beamforming (i.e. antenna virtualization) canbe implemented across the elevation dimension, it is unable to reap thepotential gain offered by the spatial and frequency selective nature ofthe channel.

FIG. 9 illustrates another numbering of TX antenna elements 900 (orTXRU) according to embodiments of the present disclosure. The embodimentshown in FIG. 9 is for illustration only. Other embodiments could beused without departing from the scope of the present disclosure.

In certain embodiments, eNB is equipped with 2D rectangular antennaarray (or TXRUs), comprising M rows and N columns with P=2 polarized,wherein each element (or TXRU) is indexed with (m, n, p), and m=0, . . ., M-1, n=0, . . . , N-1, p=0, . . . , P-1, as illustrated in FIG. 9 withM=N=4. When the example shown in FIG. 7 represents a TXRU array, a TXRUcan be associated with multiple antenna elements. In one example(1-dimensional (1D) subarray partition), an antenna array comprising acolumn with a same polarization of a 2D rectangular array is partitionedinto M groups of consecutive elements, and the M groups correspond tothe M TXRUs in a column with a same polarization in the TXRU array inFIG. 9. In later embodiments, (M,N) is sometimes denoted as (N_(H),N_(V)) or (N₁, N₂).

In some embodiments, a UE is configured with a CSI-RS resourcecomprising Q=MNP number of CSI-RS ports, wherein the CSI-RS resource isassociated with MNP number of resource elements (REs) in a pair of PRBsin a subframe.

CSI-RS and CSI Feedback Configuration

In some embodiments, a UE is configured with a CSI-RS configuration viahigher layer, configuring Q antenna ports—antenna ports A(1) throughA(Q). The UE is further configured with CSI reporting configuration viahigher layer in association with the CSI-RS configuration.

The CSI reporting configuration includes information element (IE)indicating the CSI-RS decomposition information (or component PMI portconfiguration). The information element may comprise at least twointegers, say N₁ and N₂, which respectively indicates a first number ofantenna ports for a first dimension, and a second number of antennaports for a second dimension, wherein Q=N₁·N₂.

One example method of indicating the CSI-RS decomposition (or componentPMI port configuration) is described below.

CSIRS decomposition When Q = 8, (N₁, N₂) ∈ {(2, 4), (4, 2)}. informationor When Q = 16, (N₁, N₂) ∈ {(2, 8), (4, 4), (8, 2)}. Component PMI portWhen Q = 32, (N₁, N₂) ∈ {(8, 4), (4, 8)}. configuration

Another example method of indicating the PMI reporting decomposition isto explicitly configure Q and N₁, and implicitly configure N₂.

Component PMI port Q . . . positive even number, e.g., selected fromconfiguration {1, 2, 4, . . . , 32} N₁ . . . positive even number, e.g.,selected from {1, 2, 4, . . . , 16} N₂ = Q/N₁ . . . implicitly derivedout of explicitly configured N and N₁.

Another example method of indicating the PMI reporting decomposition isto explicitly configure N₁ and N₂, and implicitly configure Q.

Component PMI port N₁ . . . positive even number, e.g., selected fromconfiguration {1, 2, 4, . . . , 16} N₂ . . . positive even number, e.g.,selected from {1, 2, 4, . . . , 16} Q = N₁ · N₂ . . . implicitly derivedout of explicitly configured N₁ and N₂.

Another example method of indicating the PMI reporting decomposition isto explicitly configure M, N, and P, and implicitly configure Q.

Component PMI port M . . . positive even number, e.g., selected fromconfiguration {1, 2, 4, . . . , 16} N . . . positive even number, e.g.,selected from {1, 2, 4, . . . , 16} P . . . either 1 or 2 Q = M · N · P. . . implicitly derived out of explicitly configured M, N, and P.

When the UE is configured with (N₁, N₂), the UE calculates CQI with acomposite precoder constructed with two-component codebooks, N₁-Txcodebook (codebook 1) and N₂-Tx codebook (codebook 2). When W₁ and W₂are respectively are precoders of codebook 1 and codebook 2, thecomposite precoder (of size P×(rank)) is the (columnwise) Kroneckerproduct of the two, W=W₁

W₂. If PMI reporting is configured, the UE will report at least twocomponent PMI corresponding to selected pair of W₁ and W₂.

In one method, either W₁ or W₂ is further decomposed according to thedouble codebook structure. For example, W₁ is further decomposed into:

${W_{1}\left( {n,m} \right)} = {\frac{1}{p_{1}}\begin{bmatrix}v_{m} \\{\phi_{n}v_{m}}\end{bmatrix}}$

if rank 1; and

${W_{1}\left( {n,m,m^{\prime}} \right)} = {\frac{1}{p_{2}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}}\end{bmatrix}}$

if rank 2,wherein p₁ and p₂ are normalization factors to make total transmissionpower 1, v_(m) is an m-th DFT vector out of a (N₁/2)-Tx DFT codebookwith oversampling factor o₁, and φ_(n) is a co-phase. Furthermore, theindex m, m′, n determines the precoder W₁.

If the transmission rank is one (or number of transmission layers isone), then CQI will be derived with

${W = {{W_{1} \otimes W_{2}} = {\frac{1}{p_{1}}\begin{bmatrix}{v_{m} \otimes W_{2}} \\{\phi_{n}{v_{m} \otimes W_{2}}}\end{bmatrix}}}};$

and if the transmission rank is two, then CQI will be derived with

$W = {\left. {W_{1} \otimes W_{2}} \right|_{columnwiseKP} = {{\frac{1}{p_{2}}\begin{bmatrix}{v_{m} \otimes W_{2}} & {v_{m^{\prime}} \otimes W_{2}} \\{\phi_{n}{v_{m} \otimes W_{2}}} & {{- \phi_{n}}{v_{m^{\prime}} \otimes W_{2}}}\end{bmatrix}}.}}$

In one example of this method, N₁=8 and N₂=4, and the TXRUs (or theantenna ports) are numbered according to FIG. 8. In this case, W₁ isfurther decomposed into:

${W_{1}\left( {n,m} \right)} = {\frac{1}{p_{1}}\begin{bmatrix}v_{m} \\{\phi_{n}v_{m}}\end{bmatrix}}$

if rank 1; and

${W_{1}\left( {n,m,m^{\prime}} \right)} = {\frac{1}{p_{2}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}}\end{bmatrix}}$

if rank 2,wherein v_(m) is an m-th DFT vector out of a 4-Tx DFT codebook withoversampling factor 8; and

$\phi_{n} = {^{j\frac{2\pi \; n}{4}}.}$

Furthermore, with one transmission layer, CQI will be derived withprecoder

${W = {{W_{1} \otimes W_{2}} = {\frac{1}{\sqrt{8}}\begin{bmatrix}{v_{m} \otimes W_{2}} \\{\phi_{n}{v_{m} \otimes W_{2}}}\end{bmatrix}}}};$

and with two transmission layer, CQI will be derived with precoder

$W = {\left. {W_{1} \otimes W_{2}} \right|_{columnwiseKP} = {{\frac{1}{4}\begin{bmatrix}{v_{m} \otimes W_{2}} & {v_{m^{\prime}} \otimes W_{2}} \\{\phi_{n}{v_{m} \otimes W_{2}}} & {{- \phi_{n}}{v_{m^{\prime}} \otimes W_{2}}}\end{bmatrix}}.}}$

In another method, both W₁ and W₂ are further decomposed according tothe double codebook structure with two stages. The first stage codebookis used to represent WB and long-term channel, and the second stagecodebook is used to represent SB and short-term channel. For example, W₁and W₂ can be decomposed as W₁=W₁ ⁽¹⁾W₁ ⁽²⁾ and W₂=W₂ ⁽¹⁾W₂ ⁽²⁾,respectively, where:

-   -   W₁ ⁽¹⁾ and W₂ ⁽¹⁾ are the first stage codebooks; W₁ ⁽²⁾ and W₂        ⁽²⁾ are the second stage codebooks;    -   W₁ comprises of DFT vectors out of a (N₁/2)-Tx DFT codebook with        oversampling factor o₁, where the first stage codebook W₁ ⁽¹⁾        corresponds to a set of fixed number L₁ of uniformly-spaced        beams, and the second stage codebook W₂ ⁽²⁾ corresponds to        selecting one beam out of L₁ beams and applying a x-pol co-phase        φ_(n); and    -   W₂ comprises of DFT vectors out of a (N₂)-Tx DFT codebook with        oversampling factor o₂, where the first stage codebook W₂ ⁽¹⁾        corresponds to a set of fixed number L₂ of uniformly-spaced        beams, and the second stage codebook W₂ ⁽²⁾ corresponds to        selecting one beam out of L₂ beams;

In a special case, uniformly-spaced beams are consecutively-spacedbeams.

A beam grouping scheme is defined in terms of two groups of parameters,one group per dimension. A group of parameters for dimension d comprisesat least one of the following parameters: a number of antenna portsN_(d) ^(·); an oversampling factor o_(d) ^(·); a skip number s_(d) ^(·);a beam offset number f_(d) ^(·); and a number of beams L_(d).

In some embodiments, a beam group indicated by a first PMI i_(1,d) ofdimension d (corresponding to W_(d) ⁽¹⁾), is determined based upon thesefive parameters.

The total number of beams is N_(d) ^(·) o_(d) ^(·); and the beams areindexed by an integer m_(d), wherein beam m_(d), v_(m) _(d) ,corresponds to a precoding vector

${v_{m_{d}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{d}}{o_{d}N_{d}}} & \ldots & ^{j\frac{2\pi \; {m_{d}{({N_{d} - 1})}}}{o_{d}N_{d}}}\end{bmatrix}^{t}},$

m_(d)=0, . . . , N_(d) ^(·) o_(d)−1.

The first PMI of the dimension d, i_(1,d), i_(1,d)=0, . . . , N_(d) ^(·)o_(d)/s_(d)−1, can indicate any of L_(d) beams indexed by:m_(d)=f_(d)+s_(d)·i_(1,d),f_(d)+s_(d)·i_(1,d)+1, . . . ,f_(d)+s_(d)·i_(1,d)+L_(d)−1. These L_(d) beams are referred to as a beamgroup in dimension d.

In some embodiments, a UE may be configured via higher layers (e.g.,RRC) with at least one of these five parameters, wherein a subset ofparameters not configured in the same configuration may have beenpre-configured at the UE.

In one example, a UE is configured via higher layers with anoversampling factor o₂ for the second dimension in an RRC configuration,who is also pre-configured with all the other parameters: For the firstdimension: N₁=8, o₁=8, s₁=2, f₁=0, and L₁=4; and For the seconddimension: N₂=4, s₂=2, f₁=0, and L₁=4;

Oversampling factor o₂ for the second dimension Eumerated {1, 2, 4}

In this case, the beams in the beam group indicated by the first PMI ofthe first dimension, i_(1,1), is:

${v_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\pi \; m_{1}}{32}} & ^{j\frac{6\pi \; m_{1}}{32}}\end{bmatrix}^{t}},$

m₁=2i_(1,1), 2i_(1,1)+1, 2i_(1,1)+2, 2i_(1,1)+3; and the beams in thebeam group indicated by the first PMI of the second dimension, i_(1,2),is:

${v_{m_{2}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{4o_{2}}} & ^{j\frac{4\pi \; m_{2}}{4o_{2}}} & ^{j\frac{6\pi \; m_{2}}{4o_{2}}}\end{bmatrix}^{t}},$

m₂=2i_(1,2), 2i_(1,2)+1, 2i_(1,2)+2, 2i_(1,2)+3.

In a special case of o₂=1, there is only one group of size L₂=4, whichis:

${v_{m_{2}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{4}} & ^{j\frac{4\pi \; m_{2}}{4}} & ^{j\frac{6\pi \; m_{2}}{4}}\end{bmatrix}^{t}},$

m₂=0, 1, 2, 3. In this special case, the UE does not (need to) reporti_(1,2).

In another example, a UE is configured via higher layers with twonumbers of beams, L₁ and L₂ respectively for the first and the seconddimension in an RRC configuration, who is also pre-configured with allthe other parameters. For the first dimension: N₁=8, o₁=8, s₁=2, f₁=0;and for the second dimension: N₂=4, o₂=4, s₂=2, f₁=0.

Number of beams for the first dimension L₁ Eumerated {1, 2, 4} Number ofbeams for the second dimension L₁ Eumerated {1, 2, 4}

In this case, the beams in the beam group indicated by the first PMI ofthe first dimension, i_(1,1), is:

${v_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\pi \; m_{1}}{32}} & ^{j\frac{6\pi \; m_{1}}{32}}\end{bmatrix}^{t}},$

m₁=2i_(1,1), . . . , 2i_(1,1)+L₁−1; and the beams in the beam groupindicated by the first PMI of the second dimension, i_(1,2), is:

${v_{m_{2}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{16}} & ^{j\frac{4\pi \; m_{2}}{16}} & ^{j\frac{6\pi \; m_{2}}{16}}\end{bmatrix}^{t}},$

m₂=2i_(1,2), . . . , 2i_(1,2)i_(1,2)+L₂−1.

In some embodiments, N₁=8 and N₂=4, and the TXRUs (or the antenna ports)are numbered according to FIG. 8. Three illustrative beam groupingschemes, referred to as Scheme 1, Scheme 2, and Scheme 3, according tothe double codebook structure are shown in FIGS. 10, 11 and 12, and therelated parameters are listed in TABLE 1.

TABLE 1 Parameters for three example beam grouping schemes A first Asecond oversampling A first number of oversampling A second numberfactor o₁ for the beams L₁ for the factor o₂ for the of beams L₂ for thefirst dimension first dimension second dimension second dimension Scheme1 8 4 4 1 Scheme 2 8 4 4 2 Scheme 3 8 2 4 2

In these schemes, a horizontal oversampling factor o₁=8 is consideredfor W₁ ⁽¹⁾ codebook and a vertical oversampling factor o₂=4 isconsidered for W₂ ⁽¹⁾ codebook. Hence, total number of beams for W₁ ⁽¹⁾codebook is

${\frac{N_{1}o_{1}}{P} = 32},$

and total number of beams for W₂ ⁽¹⁾ codebook is N₂o₂=16. FIGS. 10 to 12illustrate these 16×32 3D beams constructed by Kronecker product of eachbeam vector in W₁ ⁽¹⁾ codebook and each beam vector in W₂ ⁽¹⁾ codebookas a 16×32 grid, wherein each square correspond to a beam.

FIG. 10 illustrates a beam grouping scheme corresponding to Scheme 1 inTABLE 1 according to embodiment of the present disclosure. Theembodiment shown in FIG. 10 is for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

In Scheme 1, W₁ ⁽¹⁾ codebook is a set of uniformly-spaced 4 DFT beams(L₁=4). In the figure, a first, a second, and a third beam groups areillustrated. The first group comprises beams corresponding to beam grids(h,v)=(0,0), (1,0), (2,0), and (3,0), where h and v refer to horizontaland vertical grid indices, respectively. The second group comprisesbeams corresponding to beam grids (h,v)=(2,0), (3,0), (4,0), and (5,0).The beam groups with v=0 can be similarly constructed, and total numberof beam groups with v=0 is 16. The third group comprises beamscorresponding to beam grids (h,v)=(0,1), (1,1), (2,1), and (3,1).Continuing similarly through horizontal and vertical beam directions,16×16=256 beam groups are constructed. A beam group can be indicated bya log 2(256)=8 bit field. Note that in Scheme 1, W₁ ⁽¹⁾ corresponds tothe first stage codebook in Rel. 10 8-Tx double codebook, and W₂ ⁽¹⁾codebook is the set of single DFT beams (L₂=1).

FIG. 11 illustrates a beam grouping scheme 1100 corresponding to Scheme2 in TABLE 1 according to the embodiments of the present disclosure. Theembodiment shown in FIG. 11 is for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

In Scheme 2, W₁ ⁽¹⁾ codebook is a set of uniformly-spaced 4 DFT beams(L₁=4) and W₂ ⁽¹⁾ codebook is a set of uniformly-spaced 2 DFT beams(L₁=2). In the figure, a first, a second, and a third beam groups areillustrated. The first group comprises beams corresponding to beam grids(h,v)=(0,0), (1,0), (2,0), (3,0), (0,1), (1,1), (2,1), and (3,1). Thesecond group comprises beams corresponding to beam grids (h,v)=(2,0),(3,0), (4,0), (5,0), (2,1), (3,1), (4,1), and (5,1). The beam groupswith v=0 and 1 can be similarly constructed, and total number of beamgroups with v=0 and 1 is 16. The third group comprises beamscorresponding to beam grids (h,v)=(0,2), (1,2), (2,2), (3,2), (0,3),(1,3), (2,3), and (3,3). Continuing similarly through horizontal andvertical beam directions, 16×8=128 beam groups are constructed. A beamgroup can be indicated by a log 2(128)=7 bit field. Note that in Scheme2, W₁ ⁽¹⁾ corresponds to the first stage codebook in Rel. 10 8-Tx doublecodebook.

FIG. 12 illustrates a beam grouping scheme 1200 corresponding to Scheme3 in TABLE 1 according to embodiments of the present disclosure. Theembodiment shown in FIG. 12 is for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

In Scheme 3, both W₁ ⁽¹⁾ and W₂ ⁽¹⁾ are sets of uniformly-spaced 2 DFTbeams (L₁=L₂=2). In the figure, a first, a second, and a third beamgroups are illustrated. The first group comprises beams corresponding tobeam grids (h,v)=(0,0), (1,0), (0,1), and (1,1). The second groupcomprises beams corresponding to beam grids (h,v)=(2,0), (3,0), (2,1),and (3,1). The beam groups with v=0 and 1 can be similarly constructed,and total number of beam groups with v=0 and 1 is 16. The third groupcomprises beams corresponding to beam grids (h,v)=(0,2), (1,2), (0,3),and (1,3). Continuing similarly through horizontal and vertical beamdirections, 16×8=128 beam groups are constructed. A beam group can beindicated by a log 2(128)=7 bit field.

It should be noted that these codebooks are for illustration only. Themethod is applicable to other kinds of double codebooks.

In some embodiments, PMI indices corresponding to W₁ ⁽¹⁾ and W₂ ⁽¹⁾ areWB and long-term and that corresponding to W₁ ⁽²⁾ and W₂ ⁽²⁾ are SB andshort-term. The PMI feedback payload to indicate PMI indices for thethree schemes is shown in below TABLE 2. Both WB and SB components ofthe feedback overhead can be decomposed into two, one for azimuth andthe other for elevation.

WB components: in all three schemes, a 4-bit feedback is needed toreport azimuth component of the PMI index (H-PMI) corresponding to W₁⁽¹⁾. In Scheme 1, if V-PMI is configured as a WB component, then V-PMIis reported as a 4 bit information, which corresponds to W₂ ⁽¹⁾.Otherwise no WB V-PMI is reported (i.e., 0 bits for W₂ ⁽¹⁾). In bothSchemes 2 and 3, V-PMI is reported as a 3-bit information, whichcorresponds to W₂ ⁽¹⁾.

SB components: in all three schemes, a 2-bit feedback is needed toreport the co-phase value. To report azimuth component of the PMI index(H-PMI) corresponding to W₁ ⁽²⁾, a 2-bit indication is used in Schemes 1and 2, and a 1-bit indication is used in Scheme 3. For elevationcomponent of the PMI index (V-PMI) corresponding to W₂ ⁽²⁾, a 4-bitindication is used in Scheme 1 if SB V-PMI is configured, and a 1-bitfeedback is used in Schemes 2 and 3.

TABLE 2 Feedback overhead of different beam grouping schemes SBcomponents WB components Co- Azimuth Elevation Azimuth Elevation phasing(bits) (bits) (bits) (bits) (bits) Scheme 1 4 4 if WB 2 4 if SB 2 V-PMIis V-PMI is configured; configured; 0 otherwise 0 otherwise Scheme 2 4 32 1 2 Scheme 3 4 3 1 1 2

In some embodiments, the UE is configured with one first-stage codebookselected from multiple candidate first-stage codebooks, in which eachfirst stage codebook is associated with a set of parameters defining asingle beam grouping scheme such as Schemes 1, 2, and 3 in TABLE 1. Inone example, a beam grouping scheme may be configured via higher-layers(e.g, RRC) according to the below; or a preferred beam grouping schememay be reported by the UE.

Beam grouping scheme for the Eumerated {Scheme 1, Scheme 2, first stagecodebook Scheme 3} . . . related to schemes in TABLE 1

In some embodiments, the UE is configured with one first-stage codebookselected from multiple candidate first-stage codebooks where each firststage codebook is associated with multiple beam grouping schemes whereinexample beam grouping schemes are shown in TABLE 1. In this case, the UEcan more flexibly select SB PMI. For example, a UE may be configured toreport a first PMI based upon the first-stage codebook, comprising beamgroups constructed by Schemes 1 and 2. For this configuration, a newinformation element (IE) that can be configured in the higher-layer(e.g., RRC) can be designed as shown below, which indicates which ofschemes 1, 2 and 3 are used for constructing beam groups for first stagecodebook construction.

Selected beam grouping Eumerated {Schemes 1&2, Schemes 1&3, schemes forthe first stage Schemes 2&3} . . . related to schemes in codebook TABLE1

In this case, the total number of beam groups indicated by W₁ ⁽¹⁾ and W₂⁽¹⁾ is determined as sum of numbers of beam groups indicated by the twoschemes. For example, when schemes 1 and 3 are chosen, the total numberof beam groups is 256+128=384. A UE may report a one-bit selected beamgroup index information, as well as the first PMI i_(1,1) and i_(1,2)for the two dimensions; in this case, the first PMI is interpreteddifferently according to the reported beam group index.

In some embodiments, a UE is configured with a CSI-RS configuration viahigher layer, configuring two resources, wherein a first resource isused for CSI-RS transmissions of N₁ antenna ports—antenna ports A(1)through A(N₁), and a second resource is used for CSI-RS transmissions ofN₂ antenna ports—antenna ports B(1) through B(N₂).

When the UE is configured with (N₁, N₂), the UE calculates CQI with acomposite precoder constructed with two-component codebooks, N₁-Txcodebook (codebook 1) and N₂-Tx codebook (codebook 2). When W₁ and W₂are respectively are precoders of codebook 1 and codebook 2, thecomposite precoder (of size P×(rank), wherein P=N₁·N₂) is the Kroneckerproduct of the two, W=W₁

W₂. If PMI reporting is configured, the UE will report two component PMIcorresponding to selected pair of W₁ and W₂. The signals formed with thecomposite precoder is assumed to be transmitted on antenna ports C(1), .. . , C(P) for the purpose of deriving CQI index. The UE may also assumethat reference signals on antenna ports C(1), . . . , C(P) areconstructed by a Kronecker product of reference signals on A(1), . . . ,A(N₁) and reference signals on B(1), . . . , B(N₂). In other words:[C(1), . . . , C(P)]^(t)=[A(1), . . . , A(N₁)]^(t)

[B(1), . . . , B(N₂)]^(t).

Relation of Composite Precoder to Antenna Ports

In some embodiments, for the purpose of deriving CQI index, and PMI andRI (if configured), the UE may assume the following:

The PDSCH signals on antenna ports {7, . . . , 6+ν} would result insignals equivalent to corresponding symbols transmitted on antenna ports{15, . . . , 14+P}, as given by

${\begin{bmatrix}{y^{(15)}(i)} \\\vdots \\{y^{({14 + P})}(i)}\end{bmatrix} = {{W(i)}\begin{bmatrix}{x^{(0)}(i)} \\\vdots \\{x^{({\upsilon - 1})}(i)}\end{bmatrix}}},$

where x(i)=[x⁽⁰⁾ (i) . . . x^((ν−1)) (i)]^(T) is a vector of symbolsfrom the layer mapping in subclause 6.3.3.2 of 3GPP TS 36.211, P is thenumber of antenna ports of the associated CSI-RS resource, and if P=1,W(i) is 1, otherwise W(i), of size P×ν, is the precoding matrixcorresponding to the reported PMI applicable to x(i). The correspondingPDSCH signals transmitted on antenna ports {15 . . . 14+P} would have aratio of EPRE to CSI-RS EPRE equal to the ratio given in subclause 3GPPTS 36.213.

8-Tx Double Codebook

TABLE 3 and TABLE 4 are codebooks for rank-1 and rank-2 (1-layer and2-layer) CSI reporting for UEs configured with 8 Tx antenna porttransmissions. To determine a CW for each codebook, two indices, i.e.,i₁ and i₂ have to be selected. In these precoder expressions, thefollowing two variables are used:

φ_(n)=e^(j πn/2)

v _(m)=[1 e ^(j2πm/32) e ^(j4πm/32) e ^(j6πm/32)]^(T·)

TABLE 3 Codebook for 1-layer CSI reporting using antenna ports 15 to 22i₂ i₁ 0 1 2 3 4 5 6 7 0-15 W_(2i) ₁ _(,0) ⁽¹⁾ W_(2i) ₁ _(,1) ⁽¹⁾ W_(2i)₁ _(,2) ⁽¹⁾ W_(2i) ₁ _(,3) ⁽¹⁾ W_(2i) ₁ _(+1,0) ⁽¹⁾ W_(2i) ₁ _(+1,1) ⁽¹⁾W_(2i) ₁ _(+1,2) ⁽¹⁾ W_(2i) ₁ _(+1,3) ⁽¹⁾ i₂ i₁ 8 9 10 11 12 13 14 150-15 W_(2i) ₁ _(+2,0) ⁽¹⁾ W_(2i) ₁ _(+2,1) ⁽¹⁾ W_(2i) ₁ _(+2,2) ⁽¹⁾W_(2i) ₁ _(+2,3) ⁽¹⁾ W_(2i) ₁ _(+3,0) ⁽¹⁾ W_(2i) ₁ _(+3,1) ⁽¹⁾ W_(2i) ₁_(+3,2) ⁽¹⁾ W_(2i) ₁ _(+3,3) ⁽¹⁾${{{where}\mspace{14mu} W_{m,n}^{(1)}} = {\frac{1}{\sqrt{8}}\begin{bmatrix}v_{m} \\{\phi_{n}v_{m}}\end{bmatrix}}},$

If the most recently reported RI=1, m and n are derived with the twoindices i₁ and i₂ according to TABLE 3, resulting in a rank-1 precoder,

$W_{m,n}^{(1)} = {{\frac{1}{\sqrt{8}}\begin{bmatrix}v_{m} \\{\phi_{n}v_{m}}\end{bmatrix}}.}$

TABLE 4 Codebook for 2-layer CSI reporting using antenna ports 15 to 22i₂ i₁ 0 1 2 3 0-15 W_(2i) ₁ _(,2i) ₁ _(,0) ⁽²⁾ W_(2i) ₁ _(,2i) ₁ _(,1)⁽²⁾ W_(2i) ₁ _(+1,2i) ₁ _(+1,0) ⁽²⁾ W_(2i) ₁ _(+1,2i) ₁ _(+1,1) ⁽²⁾ i₂i₁ 4 5 6 7 0-15 W_(2i) ₁ _(+2,2i) ₁ _(+2,0) ⁽²⁾ W_(2i) ₁ _(+2,2i) ₁_(+2,1) ⁽²⁾ W_(2i) ₁ _(+3,2i) ₁ _(+3,0) ⁽²⁾ W_(2i) ₁ _(+3,2i) ₁ _(+3,1)⁽²⁾ i₂ i₁ 8 9 10 11 0-15 W_(2i) ₁ _(,2i) ₁ _(+1,0) ⁽²⁾ W_(2i) ₁ _(,2i) ₁_(+1,1) ⁽²⁾ W_(2i) ₁ _(+1,2i) ₁ _(+2,0) ⁽²⁾ W_(2i) ₁ _(+1,2i) ₁ _(+2,1)⁽²⁾ i₂ i₁ 12 13 14 15 0-15 W_(2i) ₁ _(,2i) ₁ _(+3,0) ⁽²⁾ W_(2i) ₁ _(,2i)₁ _(+3,1) ⁽²⁾ W_(2i) ₁ _(+1,2i) ₁ _(+3,0) ⁽²⁾ W_(2i) ₁ _(+1,2i) ₁_(+3,1) ⁽¹⁾${{where}\mspace{14mu} W_{m,m^{\prime},n}^{(2)}} = {\frac{1}{4}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}}\end{bmatrix}}$

If the most recently reported RI=2, m, m′ and n are derived with the twoindices i₁ and i₂ according to TABLE 4, resulting in a rank-2 precoder,

$W_{m,m^{\prime},n}^{(2)} = {{\frac{1}{4}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}}\end{bmatrix}}.}$

It is noted that W_(m,m′,n) ⁽²⁾ is constructed such that it can be usedfor two different types of channel conditions that facilitate a rank-2transmission.

One subset of the codebook associated with i₂={0, 1, . . . , 7}comprises codewords with m=m′, or the same beams (v_(m)) are used forconstructing the rank-2 precoder:

$W_{m,m,n}^{(2)} = {{\frac{1}{4}\begin{bmatrix}v_{m} & v_{m} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m}}\end{bmatrix}}.}$

In this case, the two columns in the 2-layer precoder are orthogonal(i.e., [v_(m) φ_(n)v_(m)]^(H)·[v_(m) −φ_(n)v_(m)]=0), owing to thedifferent signs applied to φ_(n) for the two columns. These rank-2precoders are likely to be used for those UEs that can receive strongsignals along two orthogonal channels generated by the two differentlypolarized antennas.

FIG. 13 illustrates a new codebook construction 1300 according toembodiments of the present disclosure. The embodiment shown in FIG. 13is for illustration only. Other embodiments could be used withoutdeparting from the scope of the present disclosure.

In the embodiment, the new codebook construction is constructed for P=16antenna ports comprising N₁=8 and N₂=2. For each group of APscorresponding to each row (i.e., {0, 1, . . . 7} and {8, 9, . . . , 15},the channels are quantized with two indices i_(1,1) and i_(2,1),according to the 8-Tx double codebook. It is noted that the antenna(TXRU) numbering system in this example is aligned with FIG. 4A.

A co-phasing vector to apply for the two rows is constructed with a newindex k, and is equal to

$V_{k}^{(1)} = {\begin{bmatrix}1 \\u_{k}\end{bmatrix}.}$

The resulting precoders W_(m,n,k) ⁽¹⁾ and W_(m,m′,n,k) ⁽²⁾ when the mostrecently reported RI is 1 and 2 are:

$W_{m,n,k}^{(1)} = {\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,n}^{(1)} \\{u_{k}W_{m,n}^{(1)}}\end{bmatrix}}$

if RI=1;

$W_{m,m^{\prime},n,k}^{(2)} = {\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,m^{\prime},n}^{(2)} \\{u_{k}W_{m,m^{\prime},n}^{(2)}}\end{bmatrix}}$

if RI=2.

It is noted that the precoders when the most recently reported RI is >2can also be similarly constructed with applying a co-phasing vector.

-   Case 1. (RI=1) Substituting

$W_{m,n}^{(1)} = {\frac{1}{\sqrt{8}}\begin{bmatrix}v_{m} \\{\phi_{n}v_{m}}\end{bmatrix}}$

to

${W_{m,n,k}^{(1)} = {\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,n}^{(1)} \\{u_{k}W_{m,n}^{(1)}}\end{bmatrix}}},$

we obtain:

${W_{m,n,k}^{(1)}\left( {= {V_{k}^{(1)} \otimes W_{m,n}^{(1)}}} \right)} = {{\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,n}^{(1)} \\{u_{k}W_{m,n}^{(1)}}\end{bmatrix}} = {{\frac{1}{4}\begin{bmatrix}v_{m} \\{\phi_{n}v_{m}} \\{u_{k}v_{m}} \\{\phi_{n}u_{k}v_{m}}\end{bmatrix}}.}}$

Case 2. (RI=2) Substituting

$W_{m,m^{\prime},n}^{(2)} = {\frac{1}{4}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}}\end{bmatrix}}$

to

${W_{m,m^{\prime},n,k}^{(2)} = {\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,m^{\prime},n}^{(2)} \\{u_{k}W_{m,m^{\prime},n}^{(2)}}\end{bmatrix}}},$

we obtain:

${{W_{m,m^{\prime},n,k}^{(2)}\left( {= {V_{k}^{(1)} \otimes W_{m,m^{\prime},n}^{(2)}}} \right)} = {{\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,m^{\prime},n}^{(2)} \\{u_{k}W_{m,m^{\prime},n}^{(2)}}\end{bmatrix}} = {\frac{1}{\sqrt{32}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}} \\{u_{k}v_{m}} & {u_{k}v_{m^{\prime}}} \\{\phi_{n}u_{k}v_{m}} & {{- \phi_{n}}u_{k}v_{m^{\prime}}}\end{bmatrix}}}},$

where it is clarified that W_(m,m′,n,k) ⁽²⁾ is indeed a Kroneckerproduct of V_(k) ⁽¹⁾ and W_(m,m′,n) ⁽²⁾.

In one method, u_(k)=e^(jπk/2), k=0,1,2,3, which is uniformly samplingthe range of [0, 2π]. In this case, the rank-1 and rank-2 precoders areconstructed as:

$W_{m,n,k}^{(1)} = {{\frac{1}{4}\begin{bmatrix}v_{m} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} \\{^{\frac{{j\pi}\; k}{2}}v_{m}} \\{^{\frac{{j\pi}{({n + k})}}{2}}v_{m}}\end{bmatrix}}\mspace{14mu} {and}}$$W_{m,m^{\prime},n,k}^{(2)} = {{\frac{1}{\sqrt{32}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} & {{- ^{\frac{{j\pi}\; n}{2}}}v_{m^{\prime}}} \\{^{\frac{{j\pi}\; k}{2}}v_{m}} & {^{\frac{{j\pi}\; k}{2}}v_{m^{\prime}}} \\{^{\frac{{j\pi}{({n + k})}}{2}}v_{m}} & {{- ^{\frac{{j\pi}{({n + k})}}{2}}}v_{m^{\prime}}}\end{bmatrix}}.}$

In another method, u_(k)=e^(jπk/4), k=0,1,2,3, which is uniformlysampling the range of [0, π]. This method is motivated by the fact thatit would be sufficient to consider the range of [0, π] for quantizingthe elevation (or zenith) angle, when azimuth angle spans [0, 2π] Inthis case, the rank-1 and rank-2 precoders are constructed as:

$W_{m,n,k}^{(1)} = {{\frac{1}{4}\begin{bmatrix}v_{m} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} \\{^{\frac{{j\pi}\; k}{4}}v_{m}} \\{^{\frac{{j\pi}{({{2\; n} + k})}}{4}}v_{m}}\end{bmatrix}}\mspace{14mu} {and}}$$W_{m,m^{\prime},n,k}^{(2)} = {{\frac{1}{\sqrt{32}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} & {{- ^{\frac{{j\pi}\; n}{2}}}v_{m^{\prime}}} \\{^{\frac{{j\pi}\; k}{4}}v_{m}} & {^{\frac{{j\pi}\; k}{4}}v_{m^{\prime}}} \\{^{\frac{{j\pi}{({{2\; n} + k})}}{4}}v_{m}} & {{- ^{\frac{{j\pi}{({{2n} + k})}}{4}}}v_{m^{\prime}}}\end{bmatrix}}.}$

FIG. 14 illustrates another new codebook construction according toembodiments of the present disclosure. The embodiment shown in FIG. 14is for illustration only. Other embodiments could be used withoutdeparting from the scope of the present disclosure.

The codebook construction is the same as FIG. 13, except for the secondcolumn of the composite 16-Tx rank-2 precoder. According to thisconstruction, the rank-2 precoder matrix is:

${W_{m,m^{\prime},n,k}^{(2)} = {{\frac{1}{\sqrt{2}}\begin{bmatrix}{\frac{1}{4}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}}\end{bmatrix}} \\{\frac{1}{4}\begin{bmatrix}{u_{k}v_{m}} & {{- u_{k}}v_{m^{\prime}}} \\{\phi_{n}u_{k}v_{m}} & {\phi_{n}u_{k}v_{m^{\prime}}}\end{bmatrix}}\end{bmatrix}} = {\frac{1}{\sqrt{32}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}} \\{u_{k}v_{m}} & {{- u_{k}}v_{m^{\prime}}} \\{\phi_{n}u_{k}v_{m}} & {\phi_{n}u_{k}v_{m^{\prime}}}\end{bmatrix}}}},$

where u_(k)=e^(jπk/2), k=0,1,2,3 or u_(k)=e^(jπk/4), k=0,1,2,3.

FIG. 15 illustrates a new codebook construction for P=32 antenna portscomprising N₁=8 and N₂=4, according to embodiments of the presentdisclosure. The embodiment shown in FIG. 15 is for illustration only.Other embodiments could be used without departing from the scope of thepresent disclosure.

The codebook is constructed under the same principle as FIG. 13. In thiscase, the co-phasing to be applied to the four rows is a 4×1 vector,V_(k) ⁽¹⁾=[1 u_(k) u_(2k) u_(3k)]^(t), where u_(k)=e^(jπk/2),k=0,1,2,3or u_(k)=e^(jπk/4),k=0,1,2,3. In this case, the rank-1 and rank-2precoder is constructed as:

${{W_{m,n,k}^{(1)}\left( {= {V_{k}^{(1)} \otimes W_{m,n}^{(1)}}} \right)} = {\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,n}^{(1)} \\{u_{k}W_{m,n}^{(1)}} \\{u_{2\; k}W_{m,n}^{(1)}} \\{u_{3\; k}W_{m,n}^{(1)}}\end{bmatrix}}};$${W_{m,m^{\prime},n,k}^{(2)}\left( {= {V_{k}^{(1)} \otimes W_{m,m^{\prime},n}^{(2)}}} \right)} = {{\frac{1}{\sqrt{2}}\begin{bmatrix}W_{m,m^{\prime},n}^{(2)} \\{u_{k}W_{m,m^{\prime},n}^{(2)}} \\{u_{2\; k}W_{m,m^{\prime},n}^{(2)}} \\{u_{3\; k}W_{m,m^{\prime},n}^{(2)}}\end{bmatrix}}.}$

Similarly, a new codebook can be constructed according to the sameprinciple as in FIG. 13 and FIG. 15, for arbitrary numbers of N₁ and N₂;W_(m,n,k) ⁽¹⁾ and W_(m,m′,n,k) ⁽²⁾ will comprise (N₂×1) block matriceswhere each block corresponds to u_(k)W_(m,n) ⁽¹⁾, k=0,1,2, . . . , N₂;and u_(k)=e^(jπk/N) ² .

FIG. 16 shows example beam patterns constructed with [1 u_(k) u_(2k)u_(3k)]^(t) and u_(k)=e^(jπk/4),k=0,1,2,3, where antennas are spacedapart by 1.28λ, in the vertical domain. The figure shows that theelevation angle range of 90° to 115° are well-covered, the range ofwhich corresponds to typical user elevation angle distribution.

Polarization-Specific V Beams

FIG. 17 illustrates an alternate codebook construction 1700 in which twodifferent vertical beams may be applied for the two polarizationsaccording to the present disclosure. The embodiment shown in FIG. 17 isfor illustration only. Other embodiments could be used without departingfrom the scope of the present disclosure.

In this exemplary figure, we have P=16 antenna ports comprising N₁=8 andN₂=2. For each group of APs corresponding to each row (i.e., {0, 1, . .. 7} and {8, 9, . . . , 15}, the channels are quantized with two indicesi₁ and i₂, according to the 8-Tx double codebook. It is noted that theantenna (TXRU) numbering system in this example is aligned with FIG. 4A.

Two co-phasing vectors or vertical beams to apply for the two rows areconstructed with two new indices k₁ and k₂, and are equal to

$V_{k_{1}}^{(1)} = {{\begin{bmatrix}1 \\u_{k_{1}}\end{bmatrix}\mspace{14mu} {and}\mspace{14mu} V_{k_{2}}^{(1)}} = {\begin{bmatrix}1 \\u_{k_{2}}\end{bmatrix}.}}$

The first vertical beam V_(k) ₁ ⁽¹⁾ is applied to antenna ports with onepolarization, shown as solid lines, and the second vertical beam V_(k) ₂⁽¹⁾ is applied to antenna ports with other polarization, shown as dashedlines. Note that the proposed idea is applicable to rank 2 (RI=2). Theresulting precoders W_(m,n,k) ₁ _(,k) ₂ ⁽¹⁾ and W_(m,m′,n,k) ₁ _(,k) ₂⁽²⁾ when the most recently reported RI is 1 and 2 are:

Case 1. (RI=1):

$W_{m,n,k_{1},k_{2}}^{(1)} = {{\frac{1}{4}\begin{bmatrix}v_{m} \\{\phi_{n}v_{m}} \\{u_{k_{1}}v_{m}} \\{\phi_{n}u_{k_{2}}v_{m}}\end{bmatrix}}.}$

Case 2. (RI=2):

${W_{m,m^{\prime},n,k_{1},k_{2}}^{(2)} = {\frac{1}{\sqrt{32}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{\phi_{n}v_{m}} & {{- \phi_{n}}v_{m^{\prime}}} \\{u_{k_{1}}v_{m}} & {u_{k_{1}}v_{m^{\prime}}} \\{\phi_{n}u_{k_{2}}v_{m}} & {{- \phi_{n}}u_{k_{2}}v_{m^{\prime}}}\end{bmatrix}}},$

where it is clarified that W_(m,n,k) ₁ _(,k) ₂ ⁽¹⁾ is indeed aconcatenation of two Kronecker product, one for each polarization, i.e.KP (V_(k) ₁ ⁽¹⁾, v_(m)) and KP (V_(k) ₂ ⁽¹⁾,φ_(n)v_(m)),

It is noted that the precoders when the most recently reported RI is >2can also be similarly constructed with applying two vertical co-phasingvectors.

In one method, for both l=1,2, u_(k) ₁ =e^(jπk) ¹ ^(/2), k₁=0,1,2,3,which is uniformly sampling the range of [0, 2πc]. In this case, therank-1 and rank-2 precoders are constructed as:

$W_{m,n,k_{1},k_{2}}^{(1)} = {{\frac{1}{4}\begin{bmatrix}v_{m} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} \\{^{\frac{{j\pi}\; k_{1}}{2}}v_{m}} \\{^{\frac{{j\pi}{({n + k_{2}})}}{2}}v_{m}}\end{bmatrix}}\mspace{14mu} {and}}$$W_{m,m^{\prime},n,k_{1},k_{2}}^{(2)} = {{\frac{1}{\sqrt{32}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} & {{- ^{\frac{{j\pi}\; n}{2}}}v_{m^{\prime}}} \\{^{\frac{{j\pi}\; k_{1}}{2}}v_{m}} & {^{\frac{{j\pi}\; k_{1}}{2}}v_{m^{\prime}}} \\{^{\frac{{j\pi}{({n + k_{2}})}}{2}}v_{m}} & {{- ^{\frac{{j\pi}{({n + k_{2}})}}{2}}}v_{m^{\prime}}}\end{bmatrix}}.}$

In another method, for both l=1,2, u_(k) ₁ =e^(jπk) ¹ ^(/4), k₁=0,1,2,3,which is uniformly sampling the range of [0, π]. This method ismotivated by the fact that it would be sufficient to consider the rangeof [0, π] for quantizing the elevation (or zenith) angle, when azimuthangle spans [0, 2π] In this case, the rank-1 and rank-2 precoders areconstructed as:

$W_{m,n,k_{1},k_{2}}^{(1)} = {{\frac{1}{4}\begin{bmatrix}v_{m} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} \\{^{\frac{{j\pi}\; k_{1}}{4}}v_{m}} \\{^{\frac{{j\pi}{({{2\; n} + k_{2}})}}{4}}v_{m}}\end{bmatrix}}\mspace{14mu} {and}}$$W_{m,m^{\prime},n,k_{1},k_{2}}^{(2)} = {{\frac{1}{\sqrt{32}}\begin{bmatrix}v_{m} & v_{m^{\prime}} \\{^{\frac{{j\pi}\; n}{2}}v_{m}} & {{- ^{\frac{{j\pi}\; n}{2}}}v_{m^{\prime}}} \\{^{\frac{{j\pi}\; k_{1}}{4}}v_{m}} & {^{\frac{{j\pi}\; k_{1}}{4}}v_{m^{\prime}}} \\{^{\frac{{j\pi}{({{2\; n} + k_{2}})}}{4}}v_{m}} & {{- ^{\frac{{j\pi}{({{2\; n} + k_{2}})}}{4}}}v_{m^{\prime}}}\end{bmatrix}}.}$

In another method, the configuration for two vertical beams allows themto be either identical or adjacent. For example, for both l=1,2 witheither u_(k) ₁ =e^(jπk) ¹ ^(/2) or e^(jπk) ¹ ^(/4), (k₁,k₂) values arejointly selected from TABLE 5. Note that compared to the previous twomethods where 4-bit indication is needed (k₁,k₂) feedback, a 3-bitindication is needed in this method.

TABLE 5 Two vertical beam index table Index (k₁, k₂) 0 (0, 0) 1 (1, 1) 2(2, 2) 3 (3, 3) 4 (0, 1) 5 (1, 2) 6 (2, 3) 7 (3, 0)

In another method, when N₂=4 and we have a double vertical codebook withoversampling factor o₂=4 and four beams in a group represented by thefirst stage vertical codebook (L₂=4), then (k₁,k₂) is derived based onTABLE 6, which is similar to indices m and m′ in rank 2 8-Tx codebook(TABLE 4). Note that here (k₁,k₂) corresponds to indices of two 4-Tx DFTbeams from the first stage vertical codebook.

TABLE 6 Two vertical beam index TABLE for double vertical codebook i₃ i₄(k₁, k₂) 0-15 0 2i₁, 2i₁ 1 2i₁ + 1, 2i₁ + 1 2 2i₁ + 2, 2i₁ + 2 3 2i₁ +3, 2i₁ + 3 4    2i₁, 2i₁ + 1 5 2i₁ + 1, 2i₁ + 2 6    2i₁, 2i₁ + 3 72i₁ + 1, 2i₁ + 3

Note that the two vertical beam idea is general and hence is applicableto other antenna port configurations such as the ones shown in FIG. 12and FIG. 13.

PMI Feedback Indices: WB V-PMI

A UE can be configured to report three PMI indices, i₁, i₂, and i₃, forinforming eNB of m, m′, n, k, used for constructing a precoder accordingto a codebook construction associated with FIG. 11 or FIG. 12 or FIG.13. In one method, i₁, i₂ correspond to precoders W_(m,n,k) ⁽¹⁾ andW_(m,m′,n) ⁽²⁾ according to the relation in TABLE 3 and TABLE 4respectively for the cases of RI=1 and RI=2; and i₃ is mapped to kaccording to relation of k=i₃.

As k=i₃ is essentially a vertical beam index, which may not changequickly over time and frequency. Hence, it is proposed to jointlyfeedback i₁ and i₃ in PUCCH feedback modes.

FIG. 18 illustrates PUCCH mode 1-1 submode 1 according to embodiments ofthe present disclosure. The embodiment shown in FIG. 18 is forillustration only. Other embodiments could be used without departingfrom the scope of the present disclosure.

In the embodiment, a UE is configured with PUCCH feedback mode 1-1submode 1. Then, the UE reports RI, i₁ and i₃ in RI reporting instances,and the UE reports i₂ and corresponding CQI in PMI/CQI reportinginstances. This is illustrated in FIG. 18, where i₁, i₂ and i₃ aredenoted as W1, W2 and W3.

For the joint encoding of RI, i₁ and i₃, two methods are designed inTABLE 7 and TABLE 8. In one method illustrated in TABLE 7, the numbersof states for RI=1 and RI=2 case are both 8, the same as Rel-10 8-Txcodebook. To jointly encode i₁ and i₃, it is proposed to uniformlysubsample i₁ with sampling factor 4, and uniformly subsample i₃ withsubsampling factor 2. In this case, the joint coding index 0, 1, . . .and 7 for RI/PMI 1/PMI 3 that is for RI=1, would correspond to (i₁,i₃)=(0, 0), (0, 1), (4, 0), (4, 1), (8, 0), (8, 1), (12, 0) and (12, 1).

TABLE 7 Joint encoding of RI, i₁ and i₃ for PUCCH mode 1-1 submode 1 Value of joint encoding of RI and the first and  the third PMI Codebookindex  RI/PMI 1/PMI 3 RI Codebook index i₁ i₃  0-7 1$4\left\lfloor \frac{I_{R\; {I/{PMI}}\; {1/{PMI}}\; 3}}{2} \right\rfloor$I_(RI/PMI 1/PMI 3) mod 2   8-15 2$4\left\lfloor \frac{\left( {I_{{{RI}/{PMI}}\; {1/{PMI}}\; 3} - 8} \right)}{2} \right\rfloor$I_(RI/PMI 1/PMI 3) mod 2

In another method illustrated in TABLE 8, the numbers of states for RI=1and RI=2 case are both 16, double the corresponding number of states inRel-10 8-Tx codebook. To jointly encode i₄ and i₃, it is proposed touniformly subsample i₁ with sampling factor 4, but not to subsample i₃,in order to maintain the elevation beamforming gain. In this case, thejoint coding index 0, 1, . . . and 15 for RI/PMI 1/PMI 3 that is forRI=1, would correspond to (i₁, i₃)=(0, 0), (0, 1), (0, 2), (0, 3), (4,0), (4, 1), (4, 2), (4, 3), (8, 0), (8, 1), (8, 2), (8, 3), (12, 0),(12, 1), (12, 2) and (12, 3).

TABLE 8 Joint encoding of RI, i₁ and i₃ for PUCCH mode 1-1 submode 1Value of joint encoding of RI and the first and the third PMI Codebookindex RI/PMI 1/PMI 3 RI Codebook index i₁ i₃  0-15 1$4\left\lfloor \frac{I_{R\; {I/{PMI}}\; {1/{PMI}}\; 3}}{4} \right\rfloor$I_(RI/PMI 1/PMI 3) mod 4 15-31 2$4\left\lfloor \frac{\left( {I_{{{RI}/{PMI}}\; {1/{PMI}}\; 3} - 16} \right)}{4} \right\rfloor$I_(RI/PMI 1/PMI 3) mod 4

FIG. 19 illustrates an UE elevation angle distribution in cellularwireless systems, in urban macro (UMa) and urban micro (UMi) cases. Theelevation angle (θ) is defined in such a way that to the zenith is zerodegree, and to the horizon is 90 degrees. In most cases, base stationserves UEs below the base station antennas, in which case the elevationangle is 90 degrees or larger. This intuition is verified by simulationresults, as shown on the right side of FIG. 19. As for V_(k) ⁽¹⁾precoders, [1 1] and [1 j] are most frequently chosen, each of whichrespectively corresponds to an elevation angle of 90 degrees and anangle between 90 degrees and 180 degrees. In some embodiments, the V_(k)⁽¹⁾ codebook comprises two precoders:

$\left\{ {{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\1\end{bmatrix}},{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\j\end{bmatrix}}} \right\},$

so that UE can recommend one of the two elevation steering angles ofθ=90° and 90°<θ<180°.

In some embodiments, V_(k) ⁽¹⁾ codebook comprises four precoders as inother embodiments of the current disclosure, and a UE can report acodebook index out of k=0, 1, 2, 3 when the PMI is reported on PUSCH.When the PMI is reported on PUCCH and when a certain feedback mode isconfigured, a UE reports a codebook index out of a subsampled set.

In one method, the subsampled set corresponds to

$\left\{ {{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\1\end{bmatrix}},{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\j\end{bmatrix}}} \right\},$

so that UE can recommend one of the two elevation steering angles ofθ=90° and 90°<θ<180°.

In another method, the subsampled set corresponds to

$\left\{ {{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\1\end{bmatrix}},{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\{- 1}\end{bmatrix}}} \right\},$

so that UE can recommend one of the two precoders separated farthest inthe angular domain. This method can improve MU-MIMO throughput, when eNBreceives PMI constructed according to this method and applies therecommended precoders in the MU-MIMO transmissions.

In another method, the subsampled set is higher-layer configured, e.g.,between

${\left\{ {{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\1\end{bmatrix}},{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\j\end{bmatrix}}} \right\} \mspace{14mu} {and}\mspace{14mu} \left\{ {{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\1\end{bmatrix}},{\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\{- 1}\end{bmatrix}}} \right\}},$

PMI Feedback Indices: SB V-PMI

A UE can be configured to report three PMI indices, i_(i), i₂, and i₃,for informing eNB of m, m′, n, k, used for constructing a precoderaccording to a codebook construction associated with FIG. 13 or FIG. 14or FIG. 15. In one method, i_(i), i₂ correspond to precoders W_(m,n,k)⁽¹⁾ and W_(m,m′,n) ⁽²⁾ according to the relation in TABLE 3 and TABLE 4respectively for the cases of RI=1 and RI=2; and i₃ is mapped to kaccording to relation of k=i₃.

To adapt to the fast variation in the vertical channel directions, thevertical beam index k=i₃ may need to reported per SB. It is thereforeproposed to jointly feedback i₂ and i₃ in PUCCH feedback modes.

FIGS. 20 to 22 illustrate three examples of PUCCH mode 1-1 submode 12000, 2100, and 2200 according to embodiments of the present disclosure.The embodiments shown in FIGS. 20 to 22 are for illustration only. Otherembodiments could be used without departing from the scope of thepresent disclosure.

In the embodiments, a UE is configured with PUCCH feedback mode 1-1submode 1. Then, the UE reports RI and i₁ in RI reporting instances, andthe UE reports i₂, i₃, and corresponding CQI in PMI/CQI reportinginstances. This is illustrated in FIG. 20, where i₁, i₂ and i₃ aredenoted as W1, W2 and W3.

PMI Feedback Indices: Double Structure

A UE can be configured to report four PMI indices, i_(1,1), i_(2,1),i_(1,2), and i_(2,2) corresponding to codebooks W₁ ⁽¹⁾, W₂ ⁽¹⁾, W₁ ⁽²⁾,and W₂ ⁽²⁾, respectively according to some embodiments of thisdisclosure. The eNB uses them for constructing a precoder according to acodebook construction associated with FIG. 13 or FIG. 14 or FIG. 15,where index k is derived from i_(1,2) and i_(2,2). In one method,i_(1,1), i_(2,1) correspond to precoders W_(m,m,k) ⁽¹⁾ and W_(m,m′,n)⁽²⁾ according to the relation in TABLE 3 and TABLE 4 respectively forthe cases of RI=1 and RI=2; and i_(1,2) and i_(2,2) are mapped to kaccording to relation of k=s₂i_(1,2)+i_(2,2), wherein s₂ (e.g., s₂=2) isa skipping number for the second dimension, and i_(2,2)=0, 1, . . . ,L₂−1.

According to the double codebook structure, it is proposed to jointlyfeedback (i₁, i₃) and (i₂, i₄) in PUCCH feedback modes.

In one embodiment, a UE is configured with PUCCH feedback mode 1-1submode 1. Then, the UE reports RI and (i₁, i₃) in RI reportinginstances, and the UE reports (i₂, i₄), and corresponding CQI in PMI/CQIreporting instances. This is illustrated in FIG. 21, where i₁, i₂, i₃,and i₄ are denoted as W1, W2, W3 and W4.

In another embodiment, a UE is configured with PUCCH feedback mode 1-1submode 1. Then, the UE reports RI and (i_(1,1), i_(1,2)) in RIreporting instances, and the UE reports (i_(2,1), i_(2,2)), and i_(2,1)alternatively together with the corresponding CQI in PMI/CQI reportinginstances. Note that in this mode, if the number of feedback bits inPMI/CQI reporting instances is fixed, then the UE can report a courseand a fine PMI feedback for W2: W2 reported together with W4 is a coursefeedback and W2 reported alone is a refined feedback. This isillustrated in FIG. 22, where i_(1,1), i_(2,1), i_(1,2), and i_(2,2) aredenoted as W1, W2, W3 and W4.

In one example, i_(2,1) indicates one out of 4 horizontal beams andi_(2,2) indicates one out of 2 vertical beams (for example Scheme 2 in).

In some embodiments, total number of feedback bits in PMI/CQI reportinginstances is 4, of which 2 bits are used for co-phase selection and theremaining two bits are used for selecting a composite beam, constructedby Kronecker product of a horizontal beam vector and a vertical beamvector.

In PMI/CQI reporting instances in which W2+CQI are reported, theseremaining 2 bits are used to indicate one horizontal beam out of the 4horizontal beams. This is referred to as a fine PMI because all 4 beamsare considered in the PMI selection.

On the other hand, in PMI/CQI reporting instances in which W2+W4+CQI arereported, 1 bit is used to select one vertical beam out of 2 beams and 1bit is used to select a horizontal PMI from a subsampled set of 4horizontal beams. This is referred to as a coarse PMI because a subsetof 4 beams are considered in the PMI selection. In one method (Method1), the subsampled set corresponds to beam indices {1,2} out of fourhorizontal beam indices {1,2,3,4} indicated by i₁. In another method(Method 2), the subsampled set corresponds to beam indices {1,3} out offour horizontal beam indices {1,2,3,4} indicated by i₁

A subsampling method may be indicated according to TABLE 9. In onemethod, eNB may configure the UE a subsampling method for deriving i₂.In another method, the UE may feedback a selected subsampling methodusing a 1-bit filed. Such feedback may be WB and long-term.

TABLE 9 Horizontal beam index subsample method Method Subsampledhorizontal beam index set 1 {1, 2} 2 {1, 3}

In another embodiment, a UE is configured with PUCCH feedback mode 1-1submode x, as shown in FIG. 23, for reporting i_(1,1), i_(2,1), i_(1,2),and i_(2,2) using two CSI processes: CSI processes 1 and 2. According toCSI processes 1, the UE reports RI and i_(1,1) in RI reportinginstances, and it reports i_(2,1) and the corresponding CQI in PMI/CQIreporting instances. Similarly, according to CSI processes 2, the UEreports RI and i_(1,2) in RI reporting instances, and it reports i_(2,2)and the corresponding CQI in PMI/CQI reporting instances.

In one method, the two RIs and CQIs in the CSI reports correspond to thejoint RI and joint CQI. In another method, one of them, for example CSIreport 1 includes joint RI and joint CQI, and the other report includesV-RI and V-CQI, for example. In yet another method, both or one of RIand CQI are reported only once in one of the CSI reports.

The parametrized KP double codebook described above is summarized asfollows.

In some embodiments, a UE is configured with a CSI-RS configuration viahigher layer, configuring Q antenna ports—antenna ports A(1) throughA(Q). The UE is further configured with CSI reporting configuration viahigher layer in association with the CSI-RS configuration. The CSIreporting configuration includes information element (IE) indicating theCSI-RS decomposition information (or component PMI port configuration).The information element may comprise at least two integers, say N₁ andN₂, which respectively indicates a first number or quantity of antennaports per pol for a first dimension, and a second number of antennaports per pol for a second dimension, wherein Q=P·N₁·N₂.

In some embodiments of the disclosure, the first dimension maycorrespond to the horizontal direction or columns, and the seconddimension may correspond to the vertical direction or rows, i.e.,(N₁,N₂)=(N,M).

In some embodiments of the disclosure, the first dimension maycorrespond to the vertical direction or rows, and the second dimensionmay correspond to the horizontal direction or columns, i.e.,(N₁,N₂)=(M,N).

In various embodiments, downlink signaling may indicate first and secondquantities of antenna ports. These first and second quantities ofantenna ports indicate respective quantities of antenna ports in firstand second dimensions. For example, the first quantity of antenna portsis a number or value for antenna ports in a first dimension. Forexample, the first dimension may be a vertical direction or rows or maybe the horizontal direction or columns. In another example, the secondquantity of antenna ports is a number or value for antenna ports in asecond dimension. For example, the second dimension may be a verticaldirection or rows or may be the horizontal direction or columns. Also,the first and second quantities of subset beams indicates respectivequantities of subset beams in first and second dimensions. For example,the first quantity of subset beams is a number or value for subset beamsin a first dimension.

In the rest of the disclosure, we will use notation (N₁,N₂) in place of(M,N) or (N,M). Similarly, we will use (O₁,O₂) for the oversamplingfactors in the two dimensions in place of (S_(N), S_(M)) or (S_(M),S_(N)).

In one embodiment, for each of [8], 12 and 16 Tx ports, a precodingmatrix W in the codebook is represented as:

W=W₁W₂

where:

${W_{1} = \begin{pmatrix}{X_{1} \otimes X_{2}} & 0 \\0 & {X_{1} \otimes X_{2}}\end{pmatrix}},$

W₂ FFS;

-   -   X₁ is a Ar₁×L₁ matrix with L₁ column vectors being an O₁x        oversampled DFT vector of length N₁:

${v_{l} = \begin{bmatrix}1 & ^{\frac{{j2\pi}\; l}{N_{1}O_{1}}} & \ldots & ^{\frac{{{j2\pi}{({N_{1} - 1})}}l}{N_{1}O_{1}}}\end{bmatrix}^{t}};$

-   -   X₂ is a N₂×L₂ matrix with L₂ column vectors being an O₂x        oversampled DFT vector of length N₂:

${v_{l} = \begin{bmatrix}1 & ^{\frac{{j2\pi}\; l}{N_{2}O_{2}}} & \ldots & ^{\frac{{{j2\pi}{({N_{2} - 1})}}l}{N_{2}O_{2}}}\end{bmatrix}^{t}};$

-   -   N₁ and N₂ are the numbers of antenna ports per pol in 1^(st) and        2^(nd) dimensions;    -   FFS whether to select different beams (e.g. different X1 or X2)        for the two pols;    -   FFS column selection from KP applied to W₁.

A first alternative to construct such a codebook is as follows. Tall,[square] and wide arrays are supported with a single codebook for eachof [8], 12 and 16 CSI-RS ports: For PUSCH and PUCCH reporting, acodebook subset can be separately selected via RRC signaling of codebooksubset selection parameters or a bitmap; FFS beam subsetselection/restriction and related mechanism; and FFS which and how theparameters (in TABLE 1) are related/configured.

A second alternative to construct such a codebook is as follows. Tall,square and wide port layouts are supported with parameters N₁, N_(2:)Values of N₁ and N₂ are RRC signaled. The parameters (in TABLE 10)define the codebook: Configurable oversampling factors, RRC signaled,values FFS; Other parameters are to be determined; FFS beam subsetselection/restriction and related mechanism.

TABLE 10 1: Codebook parameters Parameter per dimension RemarkOversampling factors O_(d) Determines total number of beams Q_(d) =O_(d) · N_(d), d = 1, 2 in the codebook. Beam group spacing Differenceof the leading beam indices of two adjacent beam groups Number of beamsin each beam May depend on rank and/or W1 group Beam spacing Differenceof two adjacent beam indices in each beam group

A beam grouping scheme and a codebook can be defined in terms of twogroups of parameters, one group per dimension. A group of parameters fordimension d comprises at least one of the following parameters: a numberof antenna ports per pol N_(d) ^(·); an oversampling factor O_(d) ^(·);a skip number (or beam group spacing) s_(d) (for W1); a beam offsetnumber f_(d); a beam spacing number p_(d) (for W2); and a number ofbeams (in each beam group) L_(d).

A beam group indicated by a first PMI i_(1,d) of dimension d(corresponding to W_(d) ⁽¹⁾), is determined based upon these sixparameters. The total number of beams is N_(d)·O_(d); and the beams areindexed by an integer m_(d), wherein beam m_(d), v_(m) _(d) ,corresponds to a precoding vector

${v_{m_{d}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{d}}{O_{d}N_{d}}} & \ldots & ^{j\frac{2\pi \; {m_{d}{({N_{d} - 1})}}}{O_{d}N_{d}}}\end{bmatrix}^{t}},$

m_(d)=0, . . . , N_(d)·O_(d)−1. The first PMI of the first dimensioni_(1,d), i_(1,d)=0, . . . , N_(d)·O_(d)/s_(d)−1, can indicate any ofL_(d) beams indexed by:m_(d)=f_(d)+s_(d)·i_(1,d),f_(d)+s_(d)·i_(1,d)+p_(d), . . . ,f_(d)+s_(d)·i_(1,d)+(L_(d)−1) p_(d), where these L_(d) beams arereferred to as a beam group.

In one example, N₁=4 and N₂=4. Three illustrative beam grouping schemes,referred to as Scheme 1, Scheme 2, and Scheme 3, according to the doublecodebook structure are shown in FIG. 4, FIG. 5 and FIG. 6, and theparameters are listed in TABLE 11.

TABLE 11 Parameters for three example beam grouping schemes A 1st A 1stA 1st A 2nd A 2^(nd) A 2^(nd) over-sampling beam number of overs-amplingbeam number of factor O₁ for spacing p₁ beams L₁ factor O₂ for spacingp₂ beams L₂ the 1st for the 1st for the 1^(st) the 2nd for the 2^(nd)for the 2^(nd) dimension dimension dimension dimension dimensiondimension Scheme 1 8 1 4 4 1 1 Scheme 2 8 1 1 4 1 4 Scheme 3 8 1 2 4 1 2

FIGS. 24 to 26 illustrates respective beam grouping schemes 1, 2 and 3according to embodiments of the present disclosure. The embodimentsshown in FIGS. 24 to 26 are for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

In some embodiments, the scheme is determined according to antenna(port) dimension parameters (N₁, N₂) , where N₁ and N₁ are configured bythe higher layer (RRC). In one example, if a UE is configured with (N₁,N₂)=(8,1), scheme 1 is configured; if the UE is configured (4,2), on theother hand, scheme 2 is configured.

In these schemes, a horizontal oversampling factor O₁=8 is consideredfor W₁ ⁽¹⁾ codebook and a vertical oversampling factor O₂=4 isconsidered for W₂ ⁽¹⁾ codebook. Hence, total number of beams for W₁ ⁽¹⁾codebook is N₁O₁=32, and total number of beams for W₂ ⁽¹⁾ codebook isN₂O₂=16. FIGS. 24 to 26 illustrate these 16×32 3D beams constructed byKronecker product of each beam vector in W₁ ⁽¹⁾ codebook and each beamvector in W₂ ⁽¹⁾ codebook as a 16×32 grid, wherein each squarecorrespond to a beam.

The focus of this disclosure is on the details of configuring KPcodebook based on the codebook parameters: (N_(d), O_(d), s_(d), f_(d),p_(d), L_(d)) where d=1,2.

In some embodiments: the UE is configured with a parameterized KPcodebook corresponding to the codebook parameters (N_(d), O_(d), s_(d),f_(d), p_(d), L_(d)) where d=1,2 from a master codebook by applyingcodebook subset selection. The master codebook is a large codebook withdefault codebook parameters.

In one method, the master codebook may be unique. In another method,there may be multiple master codebooks and the UE may be configured withat least one master codebook from the multiple master codebooks. Anexample of multiple master codebooks may be based on beam offset numbersf₁ and f₂ as shown in the table below. In this example, a 1-bitindication may be used to indicate the master codebook via higher layersuch as RRC.

TABLE 12 f₁ f₂ Master codebook 0 0 0 Master codebook 1 0, 1, . . . , s₁− 1 0, 1, . . . , s₂ − 1

For simplicity, it is assumed that f₁=f₁=0 (Mater codebook 0) in therest of the disclosure. However, the disclosure is applicable to othervalues of f₁ and f₂.

An example of master codebook parameters for Q=8, 12, 16, and 32 antennaports (L₁,L₂)=(4,4) are tabulated in TABLE 3. It is noted that Q=MNP inTABLE 13.

TABLE 13 Master codebook parameters for Q = 12, 16, and 32 antenna portsand (L₁, L₂) = (4, 4) Q N₁ N₂ P O₁ O₂ L₁ L₂ p₁ p₂ s₁ s₂ 8 4 1 2 8 1 4 11 1 1 1, 2, 4 8 2 2 2 2, 4, 8 2, 4, 8 4 4 1, 2 1, 2 1, 2, 4 1, 2, 4 12 32 2 2, 4, 8 2, 4, 8 4 4 1, 2 1, 2 1, 2, 4 1, 2, 4 12 2 3 2 2, 4, 8 2, 4,8 4 4 1, 2 1, 2 1, 2, 4 1, 2, 4 16 4 2 2 2, 4, 8 2, 4, 8 4 4 1, 2 1, 21, 2, 4 1, 2, 4 16 2 4 2 2, 4, 8 2, 4, 8 4 4 1, 2 1, 2 1, 2, 4 1, 2, 432 4 4 2 2, 4, 8 2, 4, 8 4 4 1, 2 1, 2 1, 2, 4 1, 2, 4 32 8 2 2 2, 4, 82, 4, 8 4 4 1, 2 1, 2 1, 2, 4 1, 2, 4

In some embodiments, the beam grouping and beam skipping parameters (s₁,s₂, p₁, and p₂) of the master codebook are fixed and hence are notconfigured. For example, they are fixed to s₁=s₂=2, and p₁=p₂=1.

In some embodiments, the master codebook parameters for Q=8, 12, 16, and32 antenna ports and (L₁,L₂)=(4,2) are according to TABLE 14, wheremultiple oversampling factors in two dimension are supported. Theremaining codebook parameters may be fixed, for example, s₁=s₂=2, andp₁=p₂=1.

TABLE 14 Master codebook parameters for Q = 12, 16, and 32 antenna portsand (L₁, L₂) = (4, 2) Q N₁ N₂ P O₁ O₂ L₁ L₂ 8 2 2 2 2, 4, 8 2, 4, 8 4 212 3 2 2 2, 4, 8 2, 4, 8 4 2 12 2 3 2 2, 4, 8 2, 4, 8 4 2 16 4 2 2 2, 4,8 2, 4, 8 4 2 16 2 4 2 2, 4, 8 2, 4, 8 4 2 32 4 4 2 2, 4, 8 2, 4, 8 4 232 8 2 2 2, 4, 8 2, 4, 8 4 2

The oversampling factor in one or both dimensions is configurableaccording to the below table.

Oversampling factor O_(d) in dimension d where d = 1, 2 2, 4, 8

In some embodiments, the master codebook parameters for Q=8, 12, 16, and32 antenna ports and (L₁,L₂)=(4,2) are according to TABLE 15, wheresingle oversampling factors in two dimension are supported. Theremaining codebook parameters may be fixed, for example, s₁=s₂=2, andp₁=p₂=1.

TABLE 15 Master codebook parameters for Q = 12, 16, and 32 antenna portsand (L₁, L₂) = (4, 2) Q N₁ N₂ P O₁ O₂ L₁ L₂ 8 2 2 2 8 8 4 2 12 3 2 2 8 84 2 12 2 3 2 8 8 4 2 16 4 2 2 8 8 4 2 16 2 4 2 8 8 4 2 32 4 4 2 8 8 4 232 8 2 2 8 8 4 2

In some embodiments, the UE may be configured with one of multiple beamgrouping schemes or (L₁,L₂) value. Depending on the configured (L₁,L₂),the other codebook parameters such as beam skipping parameters (s₁,s₂)are determined by the UE. For example, when the UE is configured with(L₁,L₂)=(4,2), then UE determines s₁=s₂=2, and when the UE is configuredwith (L₁,L₂)=(1,1), then UE determines s₁=s₂=1. The number of W1 bitsfor the former, i.e., (L₁,L₂)=(4,2), is log 2(O₁N₁/2)+log 2(O₂N₂/2),whereas it is log 2(O₁N₁)+log 2(O₂N₂) for the later (i.e.,(L₁,L₂)=(1,1)), which is correspond to 2 more bits than the former.

FIG. 27 illustrates a master codebook 2700 with example beam groups forN₁=4 and N₂=4 according to embodiments of the present disclosure. Theembodiment shown in FIG. 27 is for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

An example of the master codebook is a fine DFT codebook that isobtained by performing the KP of azimuth (1^(st) dimension) andelevation (2^(nd) dimension) DFT codebooks with large oversamplingfactors. For example, as shown in the figure, the oversampling factormay be 8 in azimuth dimension, i.e., O₁=8 and it may be 4 in elevationdimension, i.e., O₂=4. An example of the master codebook for N₁=4azimuth antenna ports and N₂=4 elevation antenna ports is shown in FIG.27. As shown, there are N₁O₁=32 azimuth DFT beams indexed by h=0,1,2, .. . , 31 and N₂O₂=16 elevation DFT beams indexed by v=0,1,2, . . . , 15.So, the total number of 2D DFT beams that are obtained by the KP of theazimuth and elevation DFT codebooks is 32×16=512.

From this 2D grid of DFT beams, beam groups of a default size areformed. An example of default size of beam groups is (L₁, L₂)=(4, 4) asin FIG. 27. The beam groups are formed based on all possible values ofs₁ and s₂. The set of all beam groups constitutes the master W1codebook. A few example beam group for s₁=1 and s₂=1 are shown in FIG.27 7 as shaded squares.

From these beam groups of default size, the beam selection andco-phasing are performed to construct pre-coding matrices correspondingto different number of layers v=1, 2, 3 . . . 8. For example, for v=1,one beam is selected from the 16 beams in a beam group and a co-phasingφ is applied from the QPSK co-phasing codebook={1,j,−1,−j} to form apre-coding vector (as shown in FIG. 27 for beam a_(0,0)). The set ofpre-coding matrices that are constructed in this manner constitute themaster W2 codebook.

In some embodiments, the master codebook is represented as a set ofmaster sub-codebooks where each master sub-codebook corresponds to aunique set of codebook parameters (N_(d), o_(d), s_(d), p_(d)) whered=1,2. For example, for the master codebooks in TABLE 13, the mastersub-codebooks may map to the codebook parameters according to thefollowing TABLE 16. For simplicity, in the table, parameters (N_(d),o_(d)) where d=1,2, are not shown since they take single valuesaccording to TABLE 13.

TABLE 16 Sub-codebook to codebook parameter mapping Sub-codebook Indexp₁ (for W2) p₂ (for W2) s₁ (for W1) s₂ (for W1) 0 1 1 1 1 1 1 2 2 1 4 32 1 4 2 2 5 2 4 6 4 1 7 4 2 8 4 4 9 1 2 1 1 . . . . . . . . . 17  4 418  2 1 1 1 . . . . . . . . . 26  4 4 27  2 2 1 1 . . . . . . . . . 35 4 4

In some embodiments, TABLE 17 is used as a rank-1 (1 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein the corresponding rank 1 precoder is

$W_{m_{1},m_{2},n}^{(1)} = {{\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}.}$

In this table, the 2^(nd) dimension beam index m₂ increases first as i₂increases.

TABLE 17 Master codebook for 1 layer CSI reporting for L₁ = L₂ = 4 i₂ 01 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾i₂ 4 5 6 7 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,3) ⁽¹⁾ i₂ 8 9 10 11 Precoder W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+2p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p)₂ _(,3) ⁽¹⁾ i₂ 12 13 14 15 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+3p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p)₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,2) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,3) ⁽¹⁾ i₂ 16-31Precoder Entries 16-31 constructed with replacing the second subscripts₁i_(1,1) with s₁i_(1,1) + p₁ in entries 0-15. i₂ 32-47 Precoder Entries32-47 constructed with replacing the second subscript s₁i_(1,1) withs₁i_(1,1) + 2p₁ in entries 0-15. i₂ 48-63 Precoder Entries 48-63constructed with replacing the second subscript s₁i_(1,1) withs₁i_(1,1) + 3p₁ in entries 0-15.

In some embodiments, TABLE 18 is used as a rank-1 (1 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein the corresponding rank 1 precoder is

$W_{m_{1},m_{2},n}^{(1)} = {{\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}.}$

In this table, the 1^(st) dimension beam index m₁ increases first as i₂increases.

TABLE 18 Master codebook for 1 layer CSI reporting for L₁ = L₂ = 4 i₂ 01 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾i₂ 4 5 6 7 Precoder W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾ i₂ 8 9 10 11 Precoder W_(s)₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p) ₁_(,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i)_(1,2) _(,3) ⁽¹⁾ i₂ 12 13 14 15 Precoder W_(s) ₁ _(i) _(1,1) _(+3p) ₁_(,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i)_(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(,2)⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾ i₂ 16-31Precoder Entries 16-31 constructed with replacing the second subscripts₂i_(1,2) with s₂i_(1,2) + p₂ in entries 0-15. i₂ 32-47 Precoder Entries32-47 constructed with replacing the second subscript s₂i_(1,2) withs₂i_(1,2) + 2p₂ in entries 0-15. i₂ 48-63 Precoder Entries 48-63constructed with replacing the second subscript s₂i_(1,2) withs₂i_(1,2) + 3p₂ in entries 0-15.

In some embodiments, the UE reports i_(2,1), i_(2,2) and n in place ofi₂, in which case m₁ and m₂ are determined as: m₁=s₁i_(i,1)+i_(2,1) andm₁=s₂i_(1,2)+i_(2,2).

In those embodiments related to TABLE 17 and TABLE 18, and other relatedembodiments, the parameters s₁, s₂, p₁, and p₂ in this table can beselected, e.g., according to TABLE 13, and it is assumed that L₁=L₂=4.Also i_(1,1)=0,1, . . . ,

$\frac{N_{1}o_{1}}{{Ps}_{1}} - 1$

and i_(1,2)=0,1, . . . ,

$\frac{N_{2}o_{2}}{s_{2}} - 1.$

The master codebook for other parameters and for more than 1 layer canbe similarly constructed.

Unified Codebook for Beamformed and Non-Precoded CSI-RS

In some embodiments, v_(m) ₁ and u_(m) ₂ to comprise a precoder

${W_{m_{1},m_{2},n}^{(1)} = {\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}},$

are differently configured depending on whether beamformed CSI-RS, ornon-precoded CSI-RS or both are configured.

In one such example with Q=16 and N₁=8 and N₂=2:

-   -   When the UE is configured with only non-precoded CSI-RS or both        types of CSI-RS, the UE is further configured to use:

${{Either}\mspace{14mu} \left( {{Alt}\mspace{14mu} 1} \right)\mspace{14mu} v_{m_{1}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\pi \; m_{1}}{32}} & ^{j\frac{6\pi \; m_{1}}{32}}\end{bmatrix}^{t}$ ${{{and}\mspace{14mu} u_{m_{2}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{32}}\end{bmatrix}^{t}};{{{{or}\left( {{Alt}\mspace{14mu} 2} \right)}\mspace{14mu} v_{m_{1}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}}\end{bmatrix}^{t}}$ ${{and}\mspace{14mu} u_{m_{2}}} = {\begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\pi \; m_{1}}{32}} & ^{j\frac{6\pi \; m_{1}}{32}}\end{bmatrix}^{t}.}$

-   -   When the UE is configured with only beamformed CSI-RS, the UE is        further configured to use:

v _(m) ₁ =e _(m) ₁ ^((4×1)) and u _(m) ₂ =e _(m) ₂ ^((2×1)) (if Alt 1 isused)

v _(m) ₁ =e _(m) ₁ ^((2×1)) and u _(m) ₂ =e _(m) ₂ ^((4×1)) (if Alt 2 isused)

-   -   Herein e_(m) ^((N×1)), m=0, 1, . . . , N−1, is an N×1 column        vector comprising with (N−1) elements with zero value and one        element with value of one. The one element with value of one is        on (m+1)-th row. For example, e₁ ^((4×1))=[0 1 0 0]^(t); and e₂        ^((4×1))=[0 0 1 0]^(t). In this case, the UE is further        configured to use i_(1,1)=i_(1,2)=0 in the table entries, and        the UE is configured to report only i₂ as PMI, and not to report        i_(1,1) and i_(1,2).

The precoding vector obtained with Alt 2 can be applied on the antennaports numbered according to FIGS. 7 and 8. In these embodiments, thefirst dimension corresponds to a longer dimension of the array; and thesecond dimension corresponds to a shorter dimension of the array. On thecontrary, the precoding vector obtained with Alt 1 can be applied on theantenna ports numbered in such a way that the first dimensioncorresponds to a shorter dimension of the array; and the seconddimension corresponds to a longer dimension of the array.

In some embodiments, the UE can identify that a configured CSI-RSresource is beamformed or non-precoded by:

-   -   Alt 1. Explicit RRC indication: The UE is configured with a        higher-layer parameter for the configured CSI-RS resource,        indicating whether the configured CSI-RS resource is beamformed        or non-precoded.    -   Alt 2. Implicit indication: The UE is configured with a        different set of CSI-RS port numbers for beamformed CSI-RS than        the non-precoded CSI-RS. In one example, the beamformed CSI-RS        takes antenna port numbers 200-207, while the non-precoded        CSI-RS takes antenna port numbers 15-30.

Embodiments on Codebook Subset Restriction

FIG. 28 illustrates the subset restriction on rank-1 i_(1,H) andi_(1,V)(or i_(1,1) and i_(1,2)) for N₁=8, N₂=4, o₁=8 and o₂=4, accordingto embodiments of the present disclosure. The embodiment shown in FIG.28 is for illustration only. Other embodiments could be used withoutdeparting from the scope of the present disclosure.

In some embodiments, the configured values of parameters (N_(d), o_(d),s_(d)) where d=1,2 are used to apply codebook subset restriction on ofthe set of i_(1,1) and i_(1,2) indices from the master codebook. Anillustration of subset restriction on rank-1 i_(1,1) and i_(1,2) indicesin terms of parameters s₁ and s₂ is shown in FIG. 28. In the figure, theshaded squares represent the rank-1 i_(1,1) and i_(1,2) indices that areobtained after subset restriction and the white squares represent theindices that are not included.

In some embodiments, the codebook subset restriction on i_(1,1) andi_(1,2) indices may be applied according to a table such as TABLE 19.Depending on the values of s_(d) where d=1,2, the subsets of i_(1,1) andi_(1,2) indices can be obtained from the table. Note that s₁=s₂=1corresponds to no subset restriction. In these embodiments it is assumedthat (i_(1,1), i_(1,2))=(i_(1,H), i_(1,V)), but the same design canapply even if (i_(1,1), i_(1,2))=(i_(1,V), i_(1,H))

TABLE 19 Subset restriction on rank-1 i_(1,H) and i_(1,V) (TABLE 17)i_(1,H) after subset s₁ restriction s₂ i_(1,V) after subset restriction1 0, 1, 2, . . . , N₁o₁/P − 1 1 0, 1, 2, . . . , N₂o₂ − 1 2 0, 2, 4, . .. , N₁o₁/P − 2 2 0, 2, 4, . . . , N₂o₂ − 2 4 0, 4, 8, . . . , N₁o₁/P − 44 0, 4, 8, . . . , N₂o₂ − 4

An example of such a table for N₁=8, N₂=4, o₁=8 and o₂=4 is shown inTABLE 20.

TABLE 20 Subset restriction on rank-1 i_(1,H) and i_(1,V) for N₁ = 8, N₂= 4, o₁ = 8 and o₂ = 4 i_(1,H) after subset Number of i_(1,V) aftersubset Number of i_(1,V) s₁ restriction i_(1,H) indices s₂ restrictionindices 1 0, 1, 2, . . . , 31 32 1 0, 1, 2, . . . , 15 16 2 0, 2, 4, . .. , 30 16 2 0, 2, 4, . . . , 14 8 4 0, 4, 8, . . . , 28 8 4 0, 4, 8, 124

In some embodiments, the configured values of parameters (N_(d), o_(d),s_(d), p_(d), L_(d)) where d=1,2 are used to apply codebook subsetrestriction on the set of rank-1 i₂ indices from the master codebook.The codebook subset restriction may be applied from a table such asTABLE 21. Depending on the values of L₁ and L_(2,) the subset of rank-1i₂ indices can be obtained from a row of the table.

Note that L₁=L₂=4 corresponds to no subset restriction. In theseembodiments it is assumed that (i_(1,1), i_(1,2))=(i_(1,H), i_(1,V)),but the same design can apply even if (i_(1,1), i_(1,2))=(i_(1,V),i_(1,H)).

TABLE 21 An illustration of subset restriction on rank-1 i₂ (TABLE 17)Beam Corresponding grouping case i₂ after subset Number of configuration(L₁, L₂) in FIG. 39 restriction i₂ indices 0 (4, 1) 1250 0-3, 16-19,32-35, 16 48-51 1 (1, 4) 1240 0-15 16 2 (2, 2) 1260 0-7, 16-23 16 3 (4,2) 1230 0-7, 16-23, 32-39, 32 48-55 4 (2, 4) 1220 0-31 32 5 (4, 4) 12100-63 64

FIG. 29 illustrates the example beam groups in the master codebookaccording to the present disclosure. The embodiment shown in FIG. 29 isfor illustration only. Other embodiments could be used without departingfrom the scope of the present disclosure.

The beam groups is in a size L₁=L₂=4 with (i_(1,1), i_(1,2))=(i_(1,H),i_(1,V))=(0,0) in the master codebook. In the FIG. 29, the four rowscorrespond to four different values for s₁ and s₂. The first columnshows the corresponding 2D index map of i_(1,H) and i_(1,V) indices. Therest of the four columns show the beam groups with (i_(1,1),i_(1,2))=(i_(1,H), i_(1,V))=(0,0) and four different values for p₁ andp₂.

FIG. 30 illustrates the subset restriction 300 on rank-1 i₂ according tothe embodiments of the present disclosure. The embodiment shown in FIG.30 is for illustration only. Other embodiments could be used withoutdeparting from the scope of the present disclosure.

Depending on the values of parameters L₁ and L₂, subset restriction onrank-1 i₂ indices can be differently applied. The codebook subsetrestriction on rank-1 i₂ indices is illustrated in terms of parametersL₁ and L₂, with an assumption that the master codebook has rank-1 i₂indices corresponding to beam grid 1210: (L₁, L₂)=(4,4).

In this case, the master codebook for i₂ comprises 16 beams, spanned by4×4 beams in the first and the second dimension s. In some embodiments,the index h and v in the figure corresponds to i_(2,1) and i_(2,2). Theshaded squares represent the rank-1 i₂ (or i_(2,1) and i_(2,2)) indicesthat are obtained after subset restriction and the white squaresrepresent the indices that are not included. In the figure, 1210, 1220,1230, 1240, 1250 and 1260 respectively correspond to a codebook subsetwhen (L₁,L₂)=(4,4), (2,4), (4,2), (1,4), (4,1) and (2,2) are configured.For example, 1050 shows that the beam group selected after the codebooksubset restriction comprises four beams in the h dimension: (v=i_(2,2)=0and h=i_(2,1)=0, 1, 2, 3).

In one method, for each dimension, a UE is configured with beam skipping(i.e., s_(d)), as illustrated in TABLE 22.

TABLE 22 Beam skipping configuration table Parameters Candidate valuesBeam skipping (i.e., s_(d)) 1, 2

In one method, for each dimension, a UE is configured with beam spacing(i.e., s_(d)), as illustrated in TABLE 23.

TABLE 23 Beam spacing configuration table Parameters Candidate valuesBeam spacing (i.e., p_(d)) 1, 2

In one method, for both dimensions, a UE can be configured with pair ofnumbers of beams in a beam group (i.e., (L₁, L₂)), so that the UE canrestrict the beam groups as illustrated in FIG. 39. In one example, theUE is configured with a beam group (i.e., (L₁, L₂)) in the higher-layeraccording to TABLE 24.

TABLE 24 Beam group configuration table Parameters Candidate valuesNumber of beams (L₁, L₂) (4, 1), (2, 2), (1, 4) (Respectivelycorresponding to 1240, 1250 and 1260)

The motivation for these methods is to support various antennaconfigurations at the eNB with minimal signaling overhead. Thisconfiguration may be applied based on the codebook subset restriction inthe form of a bit sequence. The bit sequence may consist of at least twobitmaps, one for i_(1,H) and i_(1,V) and the other for i₂.

Modification of the Legacy 8-Tx and 4-Tx Codebooks to Construct FD-MIMOMaster Codebook and CSR

In some embodiments, the antenna ports are numbered according to FIGS.5A to 5D, in which it is assumed that the first dimension for the PMIcorresponds to a longer dimension of the array and the second dimensioncorresponds to a shorter dimension of the array. When Q=16, theoversampled DFT vectors for the first dimension, u_(n), are of length 4,and the oversampled DFT vectors for the second dimension, v_(m), are oflength 2. When Q=12, the DFT vectors for the first dimension are oflength 3, and the DFT vectors for the second dimension are of length 2.

In such a case, with config A in FIG. 5A to 5D, the first dimension isfor the horizontal dimension and the second dimension is for thevertical dimension. The beam spacing p₁ for the first dimension isselected such that a narrowly spaced beams in the first dimensioncomprise a beam group, and the beam spacing p₂ for the second dimensionis selected such that a widely spaced beams in the second dimensioncomprise the beam group. For example, for this operation, p₁ and p₂ canbe chosen as: p₁=1,p₂=8. In addition, the total number of beams for thefirst and the second dimension are made the same: by selecting M′=32 andN′=32 for the two oversampled DFT vectors v_(m) and u_(n). This way, thefirst dimension comprising 4-Tx ULA has closely spaced beams, and thesecond dimension comprising 2-Tx ULA has widely spaced beams.

When the legacy parameters of s₁=2 and s₂=1 are chosen, the number ofbits for the first PMI (i_(1,1) and i_(1,2)) can be correspondinglydetermined. The range of i_(1,1)=0,1, . . . , 15 and hence 4 bits arenecessary to quantize the information when no codebook subsetrestriction is applied to this PMI. The range of i_(1,2) can be chosento be i_(1,2)=0,1, . . . , 31, and hence 5 bits are necessary toquantize the information when no codebook subset restriction is appliedto this PMI.

In order to reduce the master codebook size, new parameters can bechosen. For example, s₁=2 and s₂=2 are used, the range of both i_(1,1)and i_(1,2) are 0-15, and hence 4 bits are necessary to quantize eachinformation when no codebook subset restriction is applied to this PMI.

The configuration of (p₁=1, p₂=8) configures W1 beam group comprisingclosely spaced beams for the first dimension, and widely spaced beamsfor the second dimension. This configuration is likely to be useful forconfiguration B (tall array), especially when the column spacing islarge, e.g., 4λ or even 10λ. In configuration B, the first dimensioncorresponds to azimuth, and the second dimension corresponds toelevation. Because the beam angle variation over time and frequency iswide in the azimuth domain and the TXRU HPBW in the azimuth domain isalso wide (60 degrees), and hence it is likely that widely spacedazimuth beams will provide performance gain.

The configuration of (p₁=1, p₂=1) that configures W1 beam groupcomprising closely spaced beams for the both dimensions is useful forconfiguration A (wide array). Because the TXRU elevation beam width isnarrow, so the beam groups with narrowly spaced beams are likely toprovide performance gain.

Hence, in these embodiments, a UE may get configured with (p₁=1, p₂=1)if the serving eNB has wide array, and (p₁=1, p₂=8) if the serving eNBhas tall array in the higher layer (i.e., RRC), as illustrated in TABLE25.

TABLE 25 Beam spacing configuration Value for an information Beamspacing element (RRC) for the 1^(st) to configure p₁ and p ₂ and 2^(nd)dim (p₁, p₂) A first value . . . “wide array” (close, close) (1, 1) or“config A” A second value . . . “tall array” (close, wide) (1, 8) if M′= 32; or “config B” or (1, 4) if M′ = 16

In one method, the information element in TABLE 25 is defined in termsof (M, N, P) in FIG. 9, the first value may correspond to aconfiguration with N>M, and the second value may correspond to aconfiguration with N<M. When Q=16, (M,N)=(2,4) corresponds to the firstvalue; and (4,2) corresponds to the second value.

Codebook Subset Restriction Bitmap Construction for W1

In some embodiments, the beam skipping s_(d) is used for determining thebitmap {b_(n) ^(d),n=0, . . . , 31} for codebook subset restriction onrank-1 i_(1,H) and i_(1,V): If b_(n) ^(d)=1, UE is configured to be ableto select i_(1,d)=n for the PMI reporting; and If b_(n) ^(d)=0, UE isconfigured such that the PMI and RI reporting is not allowed tocorrespond to precoder(s) associated with i_(i,d)=n.

In these embodiments it is assumed that (i_(1,1), i_(1,2))=(i_(1,H),i_(1,V)), but the same design can apply even if (i_(1,1),i_(1,2))=(i_(1,V), i_(1,H)).

In one method, the UE is configured in the higher layer (RRC), whichbeam skipping the UE has to use to construct for each of i_(1,d). In onesuch example, the UE can be configured with either s_(d)=2 or s_(d)=4for each of i_(1,d). Accordingly, the CSR bitmap can be constructed asin TABLE 26. It is noted that similar CSR bitmap tables can bestraightforwardly constructed if other values such as 1 or 8 are alsoallowed to be configured for s_(d).

In some embodiment, the number of bits to be reported for i_(1,d)changes dependent upon the configured value of s_(d). In one example,when s_(d)=2, 4 bit information is reported for i_(1,d); on the otherhand when s_(d)=4, 3 bit information is reported for i_(1,d). Withreducing number of bits to feedback, the CSI decoding reliability at theeNB can be improved.

TABLE 26 Codebook subset restriction on rank-1 i_(1,H) and i_(1,V) forN₁ = 8, N₂ = 4, o₁ = o₂ = 8 Number of bits assigned Number of fori_(1,H) (or i_(1,V)) i_(1,H) i_(1,H) s₁ after subset (or i_(1,V)) (ori_(1,V)) (or s₂) restriction Bitmap b_(n) ^(d), n = 0, . . . , 31indices reporting 2 0, 2, 4, . . . , 30 $\quad\left\{ \begin{matrix}{{b_{n}^{d} = 1},} & {{n\; {mod}\; 2} = 0} \\{{b_{n}^{d} = 0},} & {{n\; {mod}\; 2} = 1}\end{matrix} \right.$ 16 4 4 0, 4, 8, . . . , 28$\quad\left\{ \begin{matrix}{{b_{n}^{d} = 1},} & {{n\; {mod}\; 4} = 0} \\{{b_{n}^{d} = 0},} & {{n\; {mod}\; 4} \neq 1}\end{matrix} \right.$  8 Alt 1: 4 Alt 2: 3

Codebook Subset Restriction Bitmap Construction for W2

In some embodiments, the beam spacing p_(d) is used for determining thebitmap {g_(n) ^(d),n=0,1, . . . , 7} to indicate indices in a W2 beamgroup for rank-1 i₂: if g_(n) ^(d)=1, UE is configured to be able toselect s_(d) i_(1,d)+n for the PMI reporting; and if g_(n) ^(d)=0, UE isconfigured such that the PMI and RI reporting is not allowed tocorrespond to precoder(s) associated with s_(d)i_(1,d)−n.

In one method, the UE is configured in the higher layer (RRC), whichbeam spacing the UE has to use to construct for i₂ (or each of i_(2,1)and i_(2,2)). In one such example, the UE can be configured with eitherp_(d)=1 or p_(d)=2 for each of i_(1,d). Accordingly, the CSR bitmap canbe constructed as in TABLE 26. It is noted that similar CSR bitmaptables can be straightforwardly constructed if other values are alsoallowed to be configured for p_(d).

TABLE 27 Codebook subset restriction on W2 beam group for rank-1 i₂ p₁(or p₂) Beam Indices (I) Bitmap g_(n) ^(d), n = 0, 1, . . . , 7 1 0, 1,2, 3 $\quad\left\{ \begin{matrix}{{g_{n}^{d} = 1},} & {n \in I} \\{{g_{n}^{d} = 0},} & {n \notin I}\end{matrix} \right.$ 2 0, 2, 4, 6 $\quad\left\{ \begin{matrix}{{g_{n}^{d} = 1},} & {n \in I} \\{{g_{n}^{d} = 0},} & {n \notin I}\end{matrix} \right.$

For W2, i.e., for beam selection within the selected beam group andco-phase selection, four alternatives (Alt 1 through Alt 4) areconsidered for codebook subset restriction bitmap construction.

In some embodiments (Alt 1), the number of beams in the first dimension(L₁), the number of beams in the second dimension (L₂), and the co-phase(c) are used for determining a bitmap {c_(n), n=0,1,2, . . . , 63} forcodebook subset restriction on rank-1 i₂ (as in TABLE 18): If c_(n)=1,UE is configured to be able to select i₂=n for the PMI reporting; and ifc_(n)=0, UE is configured such that the PMI and RI reporting is notallowed to correspond to precoder(s) associated with i₂=n.

When either TABLE 18 or TABLE 19 is configured as a master codebook, theCSR bitmap is can be constructed as in TABLE 28. The CSR (L₁,L₂)=(1,4),(4,1) and (2,2) are respectively corresponding to beam grids 1240, 1250and 1260 in FIG. 30.

TABLE 28 Codebook subset restriction on rank-1 i₂ for N₁ = 8, N₂ = 4, o₁= o₂ = 8 i₂ after subset i₂ after subset restriction restriction (I) . .. according (I) . . . according to the mater to the mater Number ofcodebook in codebook in Bitmap Number of bits assigned (L₁, L₂) TABLE 18TABLE 19 c_(n), n = 0, 1, 2, . . . , 63 i₂ indices for i₂ reporting(4, 1) 0-3, 16-19, 32-35, 48-51 0-15 $\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 4 (1, 4) 0-15 0-3, 16-19, 32-35, 48-51$\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 4 (2, 2) 0-7, 16-23 0-7, 16-23$\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 4

When the UE reports i_(2,1), i_(2,2) and n in place of i₂, the valuesthat can be reported by the UE for i_(2,1) and i_(2,2) are configured tobe restricted according to the table for 1240, 1250 and 1260.

(L₁, L₂) i_(2,1) i_(2,2) (4, 1) 0, 1, 2, 3 0 (1, 4) 0 0, 1, 2, 3 (2, 2)0, 1 0, 1

Observing TABLE 28, we realize that with only these three choices for(L₁, L₂), the total number of i₂'s used with the subset restriction isonly 32. This implies that some codewords in TABLE 18 and TABLE 19 cannever be selected. Hence, we alternatively propose to reduce the size ofmaster codebook and define the codebook subset restriction in terms of(L₁, L₂) accordingly.

In these embodiments, master codebooks are alternatively defined as inTABLE 29 and TABLE 30, with fewer elements (32) than its counterparts(64) in TABLE 18 and TABLE 19. In this case, the codebook subsetrestriction can be constructed as in TABLE 31 for 1240, 1250 and 1260.

TABLE 29 Master codebook for 1 layer CSI reporting for L₁ = L₂ = 4 i₂ 01 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾i₂ 4 5 6 7 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,3) ⁽¹⁾ i₂ 8 9 10 11 Precoder W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+2p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p)₂ _(,3) ⁽¹⁾ i₂ 12 13 14 15 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+3p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p)₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,2) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,3) ⁽¹⁾ i₂ 16 17 1819 Precoder W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁_(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(+p1,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i)_(1,2) _(,3) ⁽¹⁾ i₂ 20 21 22 23 Precoder W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂_(i) _(1,2) _(+p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2)_(+p) ₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(+p) ₂_(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(+p) ₂ _(,3) ⁽¹⁾i₂ 24 25 26 27 Precoder W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂ _(i) _(1,2)_(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁_(i) _(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(+2p1,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾ i₂ 28 29 30 31 Precoder W_(s) ₁ _(i)_(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂_(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,2)⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾

TABLE 30 Master codebook for 1 layer CSI reporting for L₁ = L₂ = 4 i₂ 01 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾i₂ 4 5 6 7 Precoder W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(+p1,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i)_(1,2) _(,3) ⁽¹⁾ i₂ 8 9 10 11 Precoder W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂_(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,1)⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾ i₂ 12 13 14 15 Precoder W_(s) ₁_(i) _(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(+3p1,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂ _(i)_(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾i₂ 16 17 18 19 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,3) ⁽¹⁾ i₂ 20 21 22 23 PrecoderW_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽¹⁾ W_(s) ₁_(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(+p1,s) ₂ _(i) _(1,2) _(+p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂_(i) _(1,2) _(+p) ₂ _(,3) ⁽¹⁾ i₂ 24 25 26 27 Precoder W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s)₂ _(i) _(1,2) _(+2p) ₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+2p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂_(,3) ⁽¹⁾ i₂ 28 29 30 31 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+3p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p)₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,2) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,3) ⁽¹⁾

TABLE 31 Codebook subset restriction on rank-1 i₂ for N₁ = 8, N₂ = 4, o₁= o₂ = 8 i₂ after subset i₂ after subset restriction restriction (I) . .. according (I) . . . according to the mater to the mater Number ofcodebook in codebook in Bitmap Number of bits assigned (L₁, L₂) TABLE 29TABLE 19 c_(n), n = 0, 1, 2, . . . , 63 i₂ indices for i₂ reporting(4, 1) 0-3, 16-19, 24-31 0-15 $\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 4 (1, 4) 0-15 0-3, 16-19, 24-31$\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 4 (2, 2) 0-7, 16-23 0-7, 16-23$\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 4

In some embodiments (Alt 2), the number of beams in the first dimension(L₁), the number of beams in the second dimension (L₂), and the co-phase(φ) are used for determining the bitmap {c_(n), n=0,1,2, . . . , 15} forcodebook subset restriction on rank-1 i₂, where the bitmap {c_(n)} is ajoint bitmap for (L₁, L₂): if c_(n)=1, UE is configured to be able toselect i₂=4n+m, for all m=0,1,2,3 such that d_(m)=1, for the PMIreporting; and if c_(n)=0, UE is configured such that the PMI and RIreporting is not allowed to correspond to precoder(s) associated withi₂=4n+m, for all m=0,1,2,3. Note that there is no subset restriction (orbitmap) for the co-phase φ. The UE may assume all four co-phase values{1,j,−1,−j} to derive rank-1 i₂:

An example of the bitmap is shown below in TABLE 32.

TABLE 32 Codebook subset restriction on rank-1 i₂ for N₁ = 8, N₂ = 4, o₁= o₂ = 8 Number of bits assigned Bitmap for i₂ (L₁, L₂) I c_(n), n = 0,1, 2, . . . , 15 Number of i₂ indices reporting (4, 1) 0, 4, 8, 12$\quad{\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.}$ 16 (4 possible values for co-phase per selectedbeam pair) 4 (1, 4) 0-3 $\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 (4 possible values for co-phase per selectedbeam pair) 4 (2, 2) 0, 1, 4, 5 $\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ 16 (4 possible values for co-phase per selectedbeam pair) 4

In some embodiments (Alt 3), the number of beams in the first dimension(L₁), the number of beams in the second dimension (L₂), and the co-phase(φ) are used for determining the separate bitmaps {c_(n),n=0,1,2, . . ., 15} and {d_(m), m=0,1,2,3} for codebook subset restriction on rank-1i₂, where the bitmap {c_(n)} is a joint bitmap for (L₁, φ) and thebitmap {d_(m)} is for L₂:

-   -   If c_(n)=1, UE is configured to be able to select i₂=16└n/4┘+(n        mod 4)+4m, for all m=0,1,2,3 such that d_(m)=1, for the PMI        reporting;    -   If c_(n)=0, UE is configured such that the PMI and RI reporting        is not allowed to correspond to precoder(s) associated with bit        i₂=16└n/4┘+ (n mod 4)+4m, for all m=0,1,2,3 such that d_(m)=1;        and    -   If d_(m)=1, UE is configured to be able to select i₂=16└n/4┘+ (n        mod 4)+4m, for all n=0,1,2, . . . , 15 such that c_(n)=1, for        the PMI reporting; and    -   If d_(m)=0, UE is configured such that the PMI and RI reporting        is not allowed to correspond to precoder(s) associated with bit        i₂=16└n/4┘+ (n mod 4)+4m, for all n=0,1,2, . . . , 15 such that        c_(n)=1.

An example of the bitmap is shown below in TABLE 33.

TABLE 33 Codebook subset restriction on rank-1 i₂ for N₁ = 8, N₂ = 4, o₁= o₂ = 8 Number of bits Number assigned Bitmap of i₂ for i₂ (L₁, L₂) I JBitmap c_(n), n = 0, 1, 2, . . . , 15 d_(m), m = 0, 1, 2, 3 indicesreporting (4, 1)  0-15 0 $\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{d_{m} = 1},} & {m \in J} \\{{d_{m} = 0},} & {m \notin J}\end{matrix} \right.$ 16 4 (1, 4) 0-3 0-3 $\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{d_{m} = 1},} & {m \in J} \\{{d_{m} = 0},} & {m \notin J}\end{matrix} \right.$ 16 4 (2, 2)  0-3, 8-11 0, 1$\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{d_{m} = 1},} & {m \in J} \\{{d_{m} = 0},} & {m \notin J}\end{matrix} \right.$ 16 4

Note that the case in which UE is configured with a joint bitmap for(L₂, φ) and a bitmap for L₁ can be similarly constructed.

In some embodiments (Alt 4), the number of beams in the first dimension(L₁), the number of beams in the second dimension (L₂), and the co-phase(φ) are used for determining the separate bitmaps {c_(n),n=0,1,2,3} and{d_(m),m=0,1,2,3}, and {e_(k),k=0,1,2,3} for codebook subset restrictionon rank-1 i₂, where the bitmap {c_(n)} is for L₁, the bitmap {d_(m)} isfor L₂, and the bitmap {e_(k)} is for φ:

-   -   If c_(n)=1, UE is configured to be able to select i₂=16n+4m+k,        for all m,k=0,1,2,3 such that d_(m)=1 and e_(k)=1, for the PMI        reporting;    -   If c_(n)=0, UE is configured such that the PMI and RI reporting        is not allowed to correspond to precoder(s) associated with bit        i₂=16n+4m+k, for all m,k=0,1,2,3 such that d_(m)=1 and e_(k)=1;        and    -   If d_(m)=1, UE is configured to be able to select i₂=16n+4m+k,        for all n,k=0,1,2,3 such that c_(n)=1 and e_(k)=1, for the PMI        reporting;    -   If d_(m)=0, UE is configured such that the PMI and RI reporting        is not allowed to correspond to precoder(s) associated with bit        i₂=16n+4m+k, for all n,k=0,1,2,3 such that c_(n)=1 and e_(k)=1.    -   If e_(k)=1, UE is configured to be able to select i₂=16n+4m+k,        for all n,m=0,1,2,3 such that c_(n)=1 and d_(m)=1, for the PMI        reporting;    -   If e_(k)=0, UE is configured such that the PMI and RI reporting        is not allowed to correspond to precoder(s) associated with bit        i₂=16n+4m+k, for all n,m=0,1,2,3 such that c_(n)=1 and d_(m)=1.

An example of the bitmap is shown below in TABLE 34.

TABLE 34 Codebook subset restriction on rank-1 i₂ for N₁ = 8, N₂ = 4, o₁= o₂ = 8 Number of bits Number assigned Bitmap Bitmap Bitmap of i₂ fori₂ (L₁, L₂) I J K c_(n), n = 0, 1, 2, . . . , 15 d_(m), m = 0, 1, 2, 3e_(k), k = 0, 1, 2, 3 indices reporting (4, 1) 0-3 0 0-3$\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{d_{m} = 1},} & {m \in J} \\{{d_{m} = 0},} & {m \notin J}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{e_{k} = 1},} & {k \in K} \\{{e_{k} = 0},} & {k \notin K}\end{matrix} \right.$ 16 4 (1, 4) 0 0-3 0-3 $\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{d_{m} = 1},} & {m \in J} \\{{d_{m} = 0},} & {m \notin J}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{e_{k} = 1},} & {k \in K} \\{{e_{k} = 0},} & {k \notin K}\end{matrix} \right.$ 16 4 (2, 2) 0, 2 0, 1 0-3$\quad\left\{ \begin{matrix}{{c_{n} = 1},} & {n \in I} \\{{c_{n} = 0},} & {n \notin I}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{d_{m} = 1},} & {m \in J} \\{{d_{m} = 0},} & {m \notin J}\end{matrix} \right.$ $\quad\left\{ \begin{matrix}{{e_{k} = 1},} & {k \in K} \\{{e_{k} = 0},} & {k \notin K}\end{matrix} \right.$ 16 4

In some embodiments, the UE is further configured to restrict to reportPMI, RI and PTI within a precoder codebook subset specified by:

-   -   the bitmap b_(n) ^(d) for each dimension d (TABLE 26); (for W1)    -   the bitmap g_(n) ^(d) for each dimension d (TABLE 27); (for W2        beam group selection)    -   For W2, i.e., for beam selection within the selected beam group        and co-phase selection, four alternatives are considered in        these embodiments:        -   Alt 1 and Alt 2: the bitmap c_(n) (Alt 1: TABLE 28 or Alt 2:            TABLE 32)        -   Alt 3: bitmaps c_(n) and d_(m) (TABLE 33)        -   Alt 4: bitmaps c_(n), d_(m), and e_(k) (TABLE 34).

For a UE configured in transmission mode X, the bitmap is configured foreach CSI process and each subframe sets (if subframe sets C_(CSI,0) andC_(CSI,1) are configured by higher layers) by higher layer signaling.For a specific precoder codebook and associated transmission mode, thebitmap can specify all possible precoder codebook subsets from which theUE can assume the eNB may be using when the UE is configured in therelevant transmission mode X.

The composite bitmap (b_(n) ¹, b_(n) ², g_(n) ¹, g_(n) ², c_(n)) (or(b_(n) ¹, b_(n) ², g_(n) ¹, g_(n) ², c_(n), d_(m)) or (b_(n) ¹, b_(n) ²,g_(n) ¹, g_(n) ², c_(n), d_(m), e_(k))) forms the bit sequence a_(A)_(c) ⁻¹, . . . . , a₃,a₂,a₁,a₀ where a₀ is the LSB and a_(A) _(c) ₁ isthe MSB and where a bit value of zero indicates that the PMI and RIreporting is not allowed to correspond to precoder(s) associated withthe bit.

The association of bits to precoders for the transmission mode X forN₁=8, N₂=4, o₁=8 and o₂=8 is given as follows:

-   W1 codebook subset restriction:    -   Bit a_(n)=b_(n) ¹, where n=0,1,2, . . . , 31, is associated with        the precoder for horizontal beam skipping s₁ (e.g., s₁ ∈ {1,2})        and codebook index i_(1,H);-   Bit a_(32+n)=b_(n) ², where n=0,1,2, . . . , 31, is associated with    the precoder for vertical beam skipping s₂ (e.g., s₂ ∈ {1,2}) and    codebook index i_(1,V);-   W2 beam grouping:    -   Bit a_(64+n)=b_(n) ¹, where n=0,1,2, . . . , 31, is associated        with the precoder for horizontal beam spacing p₁ (e.g., p₁ ∈        {1,2}) and codebook index i₂;    -   Bit a_(72+n)=b_(n) ², where n=0,1,2, . . . , 31, is associated        with the precoder for vertical beam spacing p₂ (e.g., p₂ ∈        {1,2}) and codebook index i₂; and-   Four alternatives can be considered for the indexing of bits for W2    (for beam selection and co-phasing) codebook subset restriction:    -   Alt 1        -   Bit a_(80+n)=c_(n), where n=0,1,2, . . . , 63, is associated            with the beam grouping and co-phase configuration (L₁,L₂, φ)            and codebook index i₂;    -   Alt 2        -   bit a_(80+n)=c_(n), where n=0,1,2, . . . , 15, is associated            with the beam grouping configuration (L₁,L₂) and codebook            index i₂ (4 possible values {1,j,−1,−j} for co-phase per            selected beam pair);    -   Alt 3        -   bit a_(80+n)=c_(n), where n=0,1,2, . . . , 15, is associated            with the first dimension beam grouping and co-phase            configuration (L₁, φ) and codebook index i₂; and        -   bit a_(96+n)=d_(m), where m=0,1,2,3, is associated with the            second dimension beam grouping configuration (L₂) and            codebook index i₂;    -   Alt 4        -   bit a_(80+n)=c_(n), where n=0,1,2,3, is associated with the            first dimension beam grouping configuration (L₁) and            codebook index i₂;        -   bit a_(84+n)=d_(m), where m=0,1,2,3, is associated with the            second dimension beam grouping configuration (L₂) and            codebook index i₂; and        -   bit a_(88+n)=e_(k), where k=0,1,2,3, is associated with the            co-phase configuration (φ) and codebook index i₂.

FIG. 31 illustrates a flowchart 3100 for UE operation for configuringparametrized codebook according to embodiments of the presentdisclosure. The embodiment shown in FIG. 31 is for illustration only.Other embodiments could be used without departing from the scope of thepresent disclosure.

In some embodiments, if the UE is configured with at least one of beamskipping or beam grouping parameters, according to some embodiments onthis disclosure, then it uses S3105 the proposed codebook B subsetrestriction according to some embodiments of this disclosure otherwisethe UE uses S3110 the legacy codebook subset restriction.

FIG. 32 illustrates a flowchart 3200 of the overall eNB and UE operationaccording to the parameterized codebook according to the presentdisclosure. The embodiment shown in FIG. 32 is for illustration only.Other embodiments could be used without departing from the scope of thepresent disclosure.

As shown in FIG. 32, the overall operation for configuring parameterizedcodebook and PMI, RI, CQI calculation starts with eNB determining S3205at least one of beam skipping or beam grouping parameters for the UE,followed by the corresponding bit sequence determination S3210 at theeNB. The derived bit sequence is communicated to the UE via higher layersignaling such as RRC. UE receives S3215 the bit sequence and derivesS3220 the corresponding codebook. UE then uses 3225 the derived codebookfor PMI, RI, and CQI calculation, and feeds S3330 them back to the eNB.

In some embodiments, UE is configured with another codebook parameterb_(d) where d=1,2 for the beam group type in the first stage codebook(W1). For example: if b_(d)=0, the beam groups consist of closely spacedor adjacent beams in dimension d; and if b_(d)=1, the beam groupsconsist of widely spaced or orthogonal beam pairs in dimension d.

FIG. 33 illustrates an example beam group type 3300 in which beams areadjacent in both dimensions according to the present disclosure. Theembodiment shown in FIG. 29 is for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

For example, beam groups are adjacent in both dimensions, i.e., b₁=b₂=0.The beam groups 0, 1, 2, . . . , 31 represent beam groups with 2adjacent beams in horizontal and 2 adjacent beams in verticaldimensions. For example, beam group 0 consists of beams {0,1} inhorizontal and beams {0,1} in vertical.

FIGS. 34A and 34B illustrate another example beam group types 3402, 3404in which a beam group consists of orthogonal beam pairs in the first(horizontal) dimension, i.e., b₁=1, and adjacent beams in the second(vertical) dimension, i.e., b₂=1. The embodiments shown in FIGS. 34A and34B are for illustration only. Other embodiments could be used withoutdeparting from the scope of the present disclosure.

Two alternatives for the orthogonal beams can be considered: Alt 1 3402as illustrated for the farthest orthogonal beams and Alt 2 2404 for theclosest orthogonal beams. In Alt 1 3402, the beam groups 0, 1, 2, . . ., 15 represent beam groups with 2 orthogonal beam pairs in horizontaland 2 adjacent beams in vertical dimensions. For example, beam group 0consists of beams {0,1,8, 9} in horizontal and beams {0,1} in vertical.Note that two orthogonal beam pairs are shown as two separated groups.

In some embodiments, UE is configured with the parameterized KP codebookin which at least one of the codebook parameters (N_(d), o_(d), s_(d),p_(d), L_(d), b_(d)), according to some embodiments of this disclosure,is specific to the number of transmission layers (or rank).

In one method, rank 1 and rank 2 codebooks are such that the beam groupsconsist of closely spaced or adjacent beams in both horizontal andvertical dimensions for both rank 1 and rank 2 codebooks (b₁=0, b₂=0 forboth rank 1 and rank 2). In this method, a first set of codebookparameters may be the same for both codebooks, and a second set ofparameters may be different. The first set of common parameters for rank1 and 2 codebooks may be (N_(d), o_(d), L_(d), b_(d)) and the second setof different parameters may be (s_(d), p_(d)). For instance, s_(d) andp_(d) can be both 1 and 2 for rank 1 codebook, but they are 2 for rank 2codebook. An example of the two sets is shown below.

First set (common) Second set (different) Rank N₁ N₂ o₁ o₂ L₁ L₂ b₁ b₂p₁ p₂ s₁ s₂ 1 8 4 8 4 2 2 0 0 1, 2 1, 2 1, 2 1, 2 2 2 2 2 2

In another method, rank 1 and rank 2 codebooks are such that the beamgroups consist of adjacent beams in both horizontal and verticaldimensions for rank 1 codebook (b₁=0 and b₂=0 for rank 1), and bothadjacent and orthogonal beams in horizontal dimension and only adjacentbeams in vertical dimension for rank 2 codebooks (b₁=0,1 and b₂=0,1 forrank 2). In this method, a first set of codebook parameters may be thesame for both codebooks, and a second set of parameters may bedifferent. The first set of common parameters for rank 1 and 2 codebooksmay be (N_(d), o_(d), L_(d),b₂) and the second set of differentparameters may be (b₁, s_(d),p_(d)). For instance, s_(d) and p_(d) canbe both 1 and 2 for rank 1 codebook, but they are 2 for rank 2 codebook.An example of the two sets is shown below.

First set (common) Second set (different) Rank N₁ N₂ o₁ o₂ L₁ L₂ b₂ b₂p₁ p₂ s₁ s₂ 1 8 4 8 4 2 2 0 0 1, 2 1, 2 1, 2 1, 2 2 0, 1 2 2 2 2

In some embodiments, parameters related to both first stage and secondstage codebooks are rank-specific. For example, both s₁ and s₂ (W1parameters), and p₁ and p₂ (W2 parameters) may be rank-specific.

In some embodiments, parameters related to one of the first and secondstage codebooks are rank-specific. For example, s₁ and s₂ (first stageor W1 codebook) are the common, and p₁ and p₂ (second stage or W2codeook) are rank-specific.

Codebook Design for Rank 1

TABLE 35 Master codebook for 1 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0 1 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,3) ⁽¹⁾ i_(2′) 4 5 6 7 Precoder W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i)_(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(+p1,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1)_(+p1,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾ i_(2′) 8 9 10 11 Precoder W_(s) ₁ _(i)_(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂_(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,2)⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+2p1,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾ i_(2′) 12 1314 15 Precoder W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,0) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,1) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(+3p1,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(+3p1,s) ₂_(i) _(1,2) _(,3) ⁽¹⁾ i_(2′) 16-31 Precoder Entries 16-31 constructedwith replacing the second subscript s₂i_(1,2) with s₂i_(1,2) + p₂ inentries 0-15.

In some embodiments, TABLE 35 is used as a rank-1 (1 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein the corresponding rank 1 precoder is

$W_{m_{1},m_{2},n}^{(1)} = {{\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}.}$

Note that in this table, the numbering scheme 2 in is assumed. The tablefor numbering scheme 1 can be constructed similarly. In this table, the1^(st) dimension beam index m₁ increases first as i₂ increases. In analternate table, the 2^(nd) dimension beam index m₂ may increase firstas i₂ increases.

In some embodiments, Q is equal to 2N₁*N₂.

In some embodiments, the UE reports i_(2,1), i_(2,2) and n in place ofi₂, in which case m₁ and m₂ are determined as:

m ₁ =s ₁ i _(1,1) +p ₁ i _(2,1) and m ₁ =s ₂ i _(1,2) +p ₂ i _(2,2).

In those embodiments related to T6, and other related embodiments, theparameters s₁, s₂, p₁, and p₂ in this table can be selected, e.g.,according to T3, and it is assumed that (L₁, L₂)=(4, 2). Alsoi_(1,1)=0,1, . . . ,

$\frac{N_{1}O_{1}}{s_{1}} - 1$

and i_(1,2)=0,1, . . . ,

$\frac{N_{2}O_{2}}{s_{2}} - 1.$

The number of rank-1 i₂ indices in the master codebook in TABLE 6 is 32,so 5 bits are needed to report i₂ based on this master codebook.

The master codebook for other parameters and for more than 1 layer canbe similarly constructed.

Unified Codebook for Beamformed and Non-Precoded CSI-RS

In some embodiments, v_(m) ₁ and u_(m) ₂ to comprise a precoder

$W_{m_{1},m_{2},n}^{(1)} = {{\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}.}$

are differently configured depending on whether beamformed CSI-RS, ornon-precoded CSI-RS or both are configured.

In one such example with Q=16 and N₁=4 and N₂=2: When the UE isconfigured with only non-precoded CSI-RS or both types of CSI-RS, the UEis further configured to use:

Either  (Numbering  scheme  2) $v_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\pi \; m_{1}}{32}} & ^{j\frac{6\pi \; m_{1}}{32}}\end{bmatrix}^{t}$ ${{{and}\mspace{14mu} u_{m_{2}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{32}}\end{bmatrix}^{t}};{{or}\left( {{Numbering}\mspace{14mu} {scheme}\mspace{14mu} 1} \right)}$$v_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}}\end{bmatrix}^{t}$ ${{{and}\mspace{14mu} u_{m_{2}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\pi \; m_{1}}{32}} & ^{j\frac{6\pi \; m_{1}}{32}}\end{bmatrix}^{t}};$

andWhen the UE is configured with only beamformed CSI-RS, the UE is furtherconfigured to use:

-   -   v_(m) ₁ =e_(m) ₁ ^((4×1)) and u_(m) ₂ =e_(m) ₂ ^((2×1)) (if        Numbering scheme 2 is used); or    -   v_(m) ₁ =e_(m) ₁ ^((2×1)) and u_(m) ₂ =e_(m) ₂ ^((4×1)) (if        Numbering scheme 1 is used),

wherein e_(m) ^((N×1)), m=0, 1, . . . , N−1, is an N×1 column vectorcomprising with (N−1) elements with zero value and one element withvalue of one. The one element with value of one is on (m+1)-th row. Forexample, e₁ ^((4×1))=[0 1 0 0]^(t); and e₂ ^((4×1))=[0 0 1 0]^(t). Inthis case, the UE is further configured to use i_(1,1)=i_(1,2)=0 in thetable entries, and the UE is configured to report only i₂ as PMI, andnot to report i_(1,1) and i_(1,2).

The precoding vector obtained with numbering scheme 2 can be applied onthe antenna ports. In these embodiments, the first dimension correspondsto a longer dimension of the array; and the second dimension correspondsto a shorter dimension of the array. On the contrary, the precodingvector obtained with numbering scheme 1 can be applied on the antennaports numbered in such a way that the first dimension corresponds to ashorter dimension of the array; and the second dimension corresponds toa longer dimension of the array.

In some embodiments, the UE can identify that a configured CSI-RSresource is beamformed or non-precoded by:

Alt 1. Explicit RRC indication: The UE is configured with a higher-layerparameter for the configured CSI-RS resource, indicating whether theconfigured CSI-RS resource is beamformed or non-precoded; and

Alt 2. Implicit indication: The UE is configured with a different set ofCSI-RS port numbers for beamformed CSI-RS than the non-precoded CSI-RS.In one example, the beamformed CSI-RS takes antenna port numbers200-207, while the non-precoded CSI-RS takes antenna port numbers 15-30.

Rank-1 Beam Grouping

FIG. 35 illustrates alternative rank-1 beam grouping schemes 3500according to some embodiments of the present disclosure. The embodimentsshown in FIG. 35 are for illustration only. Other embodiments could beused without departing from the scope of the present disclosure.

In the embodiments, depending on the values of parameters L₁ and L₂,subset restriction on rank-1 i₂ indices can be differently applied.

A beam grouping scheme can be configured by means of codebook subsetselection (or codebook subsampling) on rank-1 i₂ indices e.g., in termsof parameters L₁ and L₂, with an assumption that the master codebook hasrank-1 i₂ indices corresponding to 810: (L₁, L₂)=(4,2). In this case,the master codebook for i₂ comprises 8 beams, spanned by 4×2 beams inthe first and the second dimensions.

In some embodiments, the 1^(st) dim and the 2^(nd) dim in the figurecorrespond to i_(2,1) and i_(2,2). The shaded (black) squares representthe rank-1 i₂ (or i_(2,1) and i_(2,2)) indices that form a beam groupand are obtained after subset restriction and the white squaresrepresent the indices that are not included in the beam group.

In the FIG. 35, 820 corresponds to a codebook subset (or a beam group)when (L₁,L₂)=(4,1) is configured and the selected beam group comprisesof 4 beams located at{(0,0), (1,0), (2,0), (3,0)}.

beam grouping schemes 830 a-830 f correspond to a codebook subset (or abeam group) when (L₁,L₂)=(2,2) is configured and different beam groupingschemes for the 4 selected beams are applied. For instance:

in beam grouping scheme 830 a, the 4 beams are located at {(0,0), (0,1),(1,0), (1,1)};

in beam grouping scheme 830 b, the 4 beams are located at {(0,0), (0,2),(1,0), (1,2)};

in beam grouping scheme 830 c, the 4 beams are located at {(0,0), (0,3),(1,0), (1,3)};

in beam grouping scheme 830 d, the 4 beams are located at {(0,0), (0,2),(1,1), (1,3)};

in beam grouping scheme 830 e, the 4 beams are located at {(0,0), (0,1),(1,2), (1,3)}; and

in beam grouping scheme 830 f, the 4 beams are located at {(0,0), (0,3),(1,1), (1,2)}.

Subset beam grouping schemes 840 a-840 d correspond to a codebook subset(or a beam group) when (L₁,L₂)=(1,2) is configured and different beamgrouping schemes for the 2 selected beams are applied. For instance:

in beam grouping scheme 840 a, the 2 beams are located at {(0,0),(0,1)};

In beam grouping scheme 840 b, the 2 beams are located at {(0,0),(1,1)};

In beam grouping scheme 840 c, the 2 beams are located at {(0,0),(2,1)}; and

In beam grouping scheme 840 d, the 2 beams are located at {(0,0),(3,1)}.

Subset beam grouping schemes 850 a-850 c correspond to a codebook subset(or a beam group) when (L₁,L₂)=(2,1) is configured and different beamgrouping schemes for the 2 selected beams are applied. For instance:

In beam grouping scheme 850 a, the 2 beams are located at {(0,0),(1,0)};

In beam grouping scheme 850 b, the 2 beams are located at {(0,0),(2,0)}; and

In beam grouping scheme 850 c, the 2 beams are located at {(0,0),(3,0)}.

Beam grouping scheme 860 corresponds to a codebook subset (or a beamgroup) when (L₁,L₂)=(1,1) is configured and the selected beam is locatedat (0,0).

The number of rank-1 i₂ indices with the subset restriction depends onthe beam grouping schemes. For the beam grouping schemes 820-830, it is16 (4×4, 4 for the beams and 4 for the co-phase), so 4 bits are neededto report i₂, for the configured beam grouping scheme from 820-830. Forthe beam grouping schemes 840-850, it is 8 (2×4, 2 for the beams and 4for the co-phase), so 3 bits are needed to report i₂, for the configuredbeam grouping scheme from 840-850. For the beam grouping scheme 860, itis 4 (1×4, 1 for the beam and 4 for the co-phase), so 2 bits are neededto report i₂, for the configured beam grouping scheme 860.

In one method, for both dimensions, a UE can be configured with pair ofnumbers of beams in a beam group (i.e., (L₁, L₂)) , so that the UE canrestrict the beam groups as illustrated in FIG. 35. In one example, theUE is configured a beam group (i.e., (L₁, L₂)) in the higher-layeraccording to TABLE 36. For each of (L₁, L₂)=(2,2), (1,2), and (2,1),there are multiple beam grouping schemes as shown in FIG. 35. In oneoption, one beam grouping scheme out of multiple beam grouping schemes830-850 is explicitly configured. In another option, it is fixed todefault schemes 830 a, 840 a, and 850 a, for example.

TABLE 36 Rank-1 beam group configuration table Parameters Candidatevalues Number of beams (L₁, L₂) (4, 1), (2, 2), (1, 2), (2, 1), (1, 1)(Respectively corresponding to 820, 830a, 840a, 850a, 860)

In another method, a UE can be configured in the higher-layer (RRC) witha beam grouping scheme, selected among a subset of beam grouping schemes820-860 in FIG. 35. For example, the subset of beam grouping schemes is{820, 830 a, 830 d, 860} in FIG. 35, and the UE is configured with onebeam grouping scheme out of this subset.

In another method, a UE can report a beam grouping scheme, selectedamong a subset of beam grouping schemes 820-860 in FIG. 35. For example,the subset of beam grouping schemes is {820, 830 a, 830 d, 860} in FIG.35, and the UE reports one beam grouping scheme out of this subset.

The motivation for these methods is to support various antennaconfigurations at the eNB with minimal signaling overhead. Thisconfiguration may be applied based on the codebook subset selection inthe form of a bit sequence. The bit sequence may consist of at least twobitmaps, one for i_(1,H) and i_(1,V) and the other for i₂. The detailsof the bitmap are provided later in the disclosure.

Codebook Design for Rank 2

In the legacy rank-2 codebook design, dual-pol propagation and azimuthangle spread have been taken into account. In the Rel12 8-Tx rank-2codebook, rank-2 precoder codebook comprises two types of rank-2precoding matrices:

Type 1. Same-beam: the two beams for the two layers are the same; and

Type 2. Different-beam: the two beams for the two layers are different.

For each selected beam pair for the two layers, two precoders can beconstructed with applying two co-phase matrices of

$\begin{bmatrix}1 & 1 \\1 & {- 1}\end{bmatrix}\mspace{14mu} {{and}\mspace{14mu}\begin{bmatrix}1 & 1 \\j & {- j}\end{bmatrix}}$

Relying on the Kronecker structure, a rank-2 master codebook can beconstructed with these two types of rank-2 precoding matrices. For the2D antenna configurations, the type 2 precoding matrices are furtherclassified into:

Type 2-1. Different-beam in horizontal only: the two beams for the twolayers are different for the horizontal component;

Type 2-2. Different-beam in vertical only: the two beams for the twolayers are different for the vertical component; and

Type 2-2. Different-beam in both horizontal & vertical: the two beamsfor the two layers are different for both horizontal and verticalcomponents.

TABLE 37 Legacy (Rel12 8-Tx) rank-2 beam index mapping for longerdimension (4 beams) Beam pair index 0 1 2 3 4 5 6 7 (first layer, (0, 0)(1, 1) (2, 2) (3, 3) (0, 1) (1, 2) (0, 3) (1, 3) second layer)

In some embodiments, TABLE 38 is used as a rank-2 (2 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein the corresponding rank 2 precoder is

$W_{m_{1},m_{2},m_{1}^{\prime},m_{1}^{\prime},n}^{(2)} = {{\frac{1}{\sqrt{2Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}}}\end{bmatrix}}.}$

Note that in this table, the numbering scheme 2 in FIG. 5 is assumed.The table for numbering scheme 1 can be constructed similarly. In thistable, the 1^(st) dimension beam index m₁ increases first as i₂increases. In an alternate table, the 2^(nd) dimension beam index m₂ mayincrease first as i₂ increases. Note that the master rank-2 codebooktable is constructed based on the legacy (Rel12) rank 2 beam pairs (T8)for the longer dimension (L₁=4) for each of the beams in the shorterdimension (L₂=2).

In those embodiments related to TABLE 38, and other related embodiments,the parameters s₁, s₂, p₁, and p₂ in this table can be selected, e.g.,according to T3 and it is assumed that (L₁, L₂)=(4, 2). Alsoi_(1,1)=0,1, . . . ,

$\frac{N_{1}O_{1}}{s_{1}} - 1$

and i_(1,2)=0,1, . . . ,

$\frac{N_{2}O_{2}}{s_{2}} - 1.$

The number of rank-2 i₂ indices in the master codebook in TABLE 38 is32, so 5 bits are needed to report i₂ based on this master codebook.

TABLE 38 Master codebook for 2 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0 1 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ W_(s) ₁_(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ i_(2′)4 5 6 7 Precoder W_(s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(,s)₁ _(i) _(1,1) _(+2p) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁_(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ i_(2′)8 9 10 11 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i1,)

⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+2p) ₁_(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ i_(2′) 12 13 14 15 Precoder W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i)

⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁_(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁_(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ i₂′ 16-31 Precoder Entries 16-31constructed with replacing the second subscript s₂i_(1,2) withs₂i_(1,2) + p₂ in entries 0-15.

indicates data missing or illegible when filed

In some embodiments, v_(m) ₁ , v_(m′) ₁ , u_(m) ₂ , and u_(m′) ₂ tocomprise a rank-2 precoder

${W_{m_{1},m_{2},m_{1}^{\prime},m_{1}^{\prime},n}^{(2)} = {\frac{1}{\sqrt{2Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}}}\end{bmatrix}}},$

are differently configured depending on whether beamformed CSI-RS, ornon-precoded CSI-RS or both are configured. When the UE is configuredwith only non-precoded CSI-RS or both types of CSI-RS, then v_(m) ₁ ,v_(m′) ₁ , u_(m) ₂ , and u_(m′) ₂ are DFT vectors of appropriate lengths(depending on numbering scheme 1 or 2) as in rank-1 codebook case, andwhen the UE is configured with only beamformed CSI-RS, then they areunit vectors of appropriate lengths.

FIG. 36 illustrate a beam combination 3600 to construct rank-2 mastercodebook based on TABLE 37 according to some embodiments of the presentdisclosure. The embodiment shown in FIG. 36 is for illustration only.Other embodiments could be used without departing from the scope of thepresent disclosure.

Utilizing the 8 beam pairs in TABLE 37 for the longer dimension (L₁=4)and for each beam in the shorter dimension (L₂=2), an 8×2 grid can beconsidered for the two dimensions as shown in FIG. 36. When beam pairindices (x, y) is selected for the 1^(st) and 2^(nd) dimensions,corresponding beam pairs are selected for the longer dimension,according to TABLE 37. For the shorter dimension, the beam indexcorresponds to the index y.

For example, applying TABLE 37 to x, with x=1 the selected beam pair forthe first dimension is (1,1) and with y=1, the selected beam for thesecond dimension is 1. Then, the corresponding rank-2 precoding matrixis:

${W_{m_{1},m_{2},m_{1}^{\prime},m_{2}^{\prime},n}^{(2)} = {\frac{1}{\sqrt{2Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}}}\end{bmatrix}}},$

where m₁=m_(1′)=s₁·i_(1,1)+p₁, and m₂=m_(2′)=s₂ ·i _(1,2)+p₂.

In general, when the selected beam pair for the first dimension is(a₀,a₁) and the selected beam for the second dimension is b₀, the beamindices m₁, m_(1′), m₂, m_(2′) are selected as:

m ₁ =s ₁ ·i _(1,1) +a ₀ ·p ₁;

m _(1′) =s ₁ ·i _(1,1) +a ₁ ·p ₁; and

m ₂ =m _(2′) =s ₂ ·i _(1,2) +b ₀ ·p ₂.

As total number of pairs for (x,y) in FIG. 36 is 16, with applying thetwo co-phases of {1,j} for φ_(n), the total number of codewords becomes32.

Embodiments on Rank-2 Beam Groupings

FIG. 37 illustrates rank-2 beam grouping schemes for rank-2 i₂ 3700according to some embodiments of the present disclosure. The embodimentshown in FIG. 37 is for illustration only. Other embodiments could beused without departing from the scope of the present disclosure.

Depending on the values of parameters L₁ and L₂, subset restriction onrank-2 i₂ indices can be differently applied. In the embodiments, a beamgrouping scheme is configured by means of codebook subset selection orcodebook subsampling on rank-2 i₂ indices e.g., in terms of parametersL₁ and L₂, with an assumption that the master codebook has rank-2 i₂indices corresponding to 1010: (L₁, L₂)=(4,2). In this case, the mastercodebook for i₂ comprises 16 rank-2 beam combinations, as shown in FIG.36 also, which are shown as a 8×2 beam combination grid where 8corresponds to the number of legacy rank-2 beam pairs for the firstdimension (L₁=4, see TABLE 37) and 2 corresponds to the 2 beams for thesecond dimension (L₂=2).

In some embodiments, the 1^(st) dim and the 2^(nd) dim in the figurecorrespond to i_(2,1) and i_(2,2). The shaded (black) squares representthe rank-2 i₂ (or i_(2,1) and i_(2,2)) indices that form a beam groupand are obtained after subset restriction and the white squaresrepresent the indices that are not included in the beam group.

In the FIG. 37, beam grouping scheme 1020 corresponds to a codebooksubset (or a beam group) when (L₁,L₂)=(4,2) is configured and theselected beam combination comprises of 4 combinations located at{(x,y)}where x={0,1,2,3} and y={0,1}. Note that this corresponds to the case inwhich the subset restriction is such that in the first dimension, onlysame beams are allowed to be used for both layers.

Beam grouping scheme 1030 corresponds to a codebook subset (or a beamgroup) when (L₁,L₂)=(4,1) is configured and the selected beamcombination comprises of 8 combinations located at{(x,0)} where x isaccording to TABLE 37; and beam grouping schemes 1040 a-1040 fcorrespond to a codebook subset (or a beam group) when (L₁,L₂)=(2,2) isconfigured and six different beam combinations are applied. Forinstance:

in beam grouping scheme 1040 a, the 8 beam combinations are {(x,y)}where x={0,1,4,5}and y={0,1};

in beam grouping scheme 1040 b, the 8 beam combinations are {(x,y)}where x={0,2,4,6}and y={0,1};

in beam grouping scheme 1040 c, the 8 beam combinations are {(x,y)}where x={0,3,4,7}and y={0,1};

in beam grouping scheme 1040 d, the 8 beam combinations are {(x,0)}where x={0,1,4,5}and {(x,1)} where x={2,3,6,7};

in beam grouping scheme 1040 e, the 8 beam combinations are {(x,0)}where x={0,3,4,7}and {(x,1)} where x={1,2,5,6}; and

in beam grouping scheme 1040 f, the 8 beam combinations are {(x,0)}where x={0,2,4,6}and {(x,1)} where x={1,3,5,7}.

Beam grouping schemes 1050 a-1050 d correspond to a codebook subset (ora beam group) when (L₁,L₂)=(1,2) is configured and four different beamcombinations are applied. For instance:

in beam grouping scheme 1050 a, the 4 beam combinations are {(x,0)}where x={0,4}and {(x,1)} where x={0,4};

in beam grouping scheme 1050 b, the 4 beam combinations are {(x,0)}where x={0,4}and {(x,1)} where x={1,5};

in beam grouping scheme 1050 c, the 4 beam combinations are {(x,0)}where x={0,4}and {(x,1)} where x={2,6}; and

in beam grouping scheme 1050 d, the 4 beam combinations are {(x,0)}where x={0,4}and {(x,1)} where x={3,7};

Beam grouping schemes 1060 a-1060 c correspond to a codebook subset (ora beam group) when (L₁,L₂)=(2,1) is configured and four different beamcombinations are applied. For instance:

in beam grouping scheme 1060 a, the 4 beam combinations are {(x,0)}where x={0,1,4,5};

in beam grouping scheme 1060 b, the 4 beam combinations are {(x,0)}where x={0,2,4,6}; and

in beam grouping scheme 1060 c, the 4 beam combinations are {(x,0)}where x={0,3,4,7}.

Beam grouping scheme 1070 corresponds to a codebook subset (or a beamgroup) when (L₁,L₂)=(1,1) is configured and the one beam is located at(0,0).

The number of rank-2 i₂ indices with the subset restriction depends onthe beam grouping schemes. For the beam grouping schemes 1020-1040, itis 16 (8×2, 4 for the beam combinations and 2 for the co-phase), so 4bits are needed to report i₂, for the configured beam grouping schemefrom 1020-1040. For the beam grouping schemes 1050-1060, it is 8 (4×2, 4for the beam combinations and 2 for the co-phase), so 3 bits are neededto report i₂, for the configured beam grouping scheme from 1050-1060.For the beam grouping scheme 1070, it is 2 (1×2, 1 for the beam and 2for the co-phase), so 1 bit is needed to report i₂, for the configuredbeam grouping scheme 1070.

In one method, for both dimensions, a UE can be configured with pair ofnumbers of beams in a beam group (i.e., (L₁, L₂)), so that the UE canrestrict the rank-2 beam combinations as illustrated in FIG. 37. In oneexample, the UE is configured a beam group (i.e., (L₁, L₂)) in thehigher-layer according to TABLE 39. For (L₁, L₂)=(2,2), (1,2), and(2,1), there are multiple beam grouping schemes. In one option, one beamgrouping scheme out of multiple beam grouping schemes is explicitlyconfigured. In another option, it is fixed to default beam groupingschemes 1040 a, 1050 a, and 1060 a, for example.

TABLE 39 Rank-2 beam group configuration table Parameters Candidatevalues Number of beams (L₁, L₂) (4, 2), (4, 1), (2, 2), (1, 2), (2, 1),(1, 1) (Respectively corresponding to 1020, 1030, 1040a, 1050a, 1060a,and 1070)

In another method, a UE can be configured in the higher-layer (RRC) witha beam grouping scheme, selected among a subset of beam grouping schemes1020-1070 in FIG. 37. For example, the subset of beam grouping schemesis {1020, 1030, 1040 a, 1070} in FIG. 37, and the UE is configured withone beam grouping scheme out of this subset.

In another method, a UE can report a beam grouping scheme, selectedamong a subset of beam grouping schemes 1020-1070 in FIG. 37. Forexample, the subset of beam grouping schemes is {1020, 1030, 1040 a,1070} in FIG. 37, and the UE reports one beam grouping scheme out ofthis subset.

As in rank-1 and rank-2 codebook cases, for the description of rank 3-8codebooks, numbering scheme 2 is assumed; the method can bestraightforwardly modified if numbering scheme 1 is assumed, withplacing different u beams on the MIMO layers instead of different vbeams in the Kronecker products.

Codebook Design for Rank 3 and Rank 4

In the Rel-12 8-Tx rank-3 codebook, rank-3 precoder codebook comprisesbeam groups with four pairs of orthogonal beams: (0,8), (2,10), (4,12),and (6,14). One orthogonal beam pair (b₀,b₁) is selected for the threelayers and three precoders can be constructed with applying the co-phasematrix of

$\quad\begin{bmatrix}1 & 1 & 1 \\1 & {- 1} & {- 1}\end{bmatrix}$

on the tuple (b₀,b₀, b₁) and (b₀,b₀, b₁), and the co-phase matrix of

$\quad\begin{bmatrix}1 & 1 & 1 \\1 & 1 & {- 1}\end{bmatrix}$

on the tuple (b₀,b₁, b₁) and (b₀,b₁, b₀).

In some embodiments, TABLE 40 is used as a rank-3 (3 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein the corresponding rank 3 precoder is either

$W_{m_{1},m_{1}^{\prime},m_{1}^{''},m_{2}}^{(3)} = {\frac{1}{\sqrt{3Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}}} & {v_{m_{1}^{''}} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}^{\prime}}} \otimes u_{m_{2}}} & {{- v_{m_{1}^{''}}} \otimes u_{m_{2}}}\end{bmatrix}}$ or${\overset{\sim}{W}}_{m_{1},m_{1}^{\prime},m_{1}^{''},m_{2}}^{(3)} = {{\frac{1}{\sqrt{3Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}}} & {v_{m_{1}^{''}} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}^{\prime}}} \otimes u_{m_{2}}} & {{- v_{m_{1}^{''}}} \otimes u_{m_{2}}}\end{bmatrix}}.}$

Note that the master rank-3 codebook table is constructed based on thelegacy (Rel12 8-Tx) rank-3 orthogonal beam pairs for the longerdimension (L₁=4) for each of the beams in the shorter dimension (L₁=2).

The number of rank-2 i₂ indices in the master codebook in TABLE 40 is32, so 5 bits are needed to report i₂ based on this master codebook.

In one method, the codebook parameters in the first dimension are legacyparameters, i.e., s₁=8, p₁=1, and i_(1,1)=0-3. In another method, theyare non-legacy parameters. The parameters for the second dimension, s₂and p₂, in this table can be selected, e.g., according to TABLE 13, andit is assumed that (L₁, L₂)=(4, 2). Also, i_(1,2)=0,1, . . . ,

$\frac{N_{2}O_{2}}{s_{2}} - 1.$

TABLE 40 Master codebook for 3 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0 1 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₁ _(i) _(1,1) _(,s) ₁_(i) _(1,1) _(+8,s) ₂ _(i) _(1,2) ⁽³⁾ W_(s) ₁ _(i) _(1,1) _(+8,s) ₁ _(i)_(1,1) _(,s) ₁ _(i) _(1,1) _(+8,s) ₂ _(i) _(1,2) ⁽³⁾ {tilde over(W)}_(s) ₁ _(i) _(1,1) _(,s) ₁ _(i) _(1,1) _(+8,s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(,s) ₁ _(i) _(1,1)_(+8,s) ₁ _(i) _(1,1) _(+8,s) ₂ _(i) _(1,2) ⁽³⁾ i_(2′) 4 5 6 7 PrecoderW_(s) ₁ _(i) _(1,1) _(+2,s) ₁ _(i) _(1,1) _(+2,s) ₁ _(i) _(1,1) _(+10,s)₂ _(i)

⁽³⁾ W_(s) ₁ _(i) _(1,1) _(+10,s) ₁ _(i) _(1,1) _(+2,s) ₁ _(i) _(1,1)_(+10,s) ₂ _(i1,)

⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(+2,s) ₁ _(i) _(1,1) _(+10,s) ₁_(i) _(1,1) _(+2,s) ₂ _(i) _(1,2) ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1)_(+2,s) ₁ _(i) _(1,1) _(+10,s) ₁ _(i) _(1,1) _(+10,s) ₂ _(i) _(1,2) ⁽³⁾i_(2′) 8 9 10 11 Precoder W_(s) ₁ _(i) _(1,1) _(+4,s) ₁ _(i) _(1,1)_(+4,s) ₁ _(i) _(1,1) _(+12,s) ₂ _(i)

⁽³⁾ W_(s) ₁ _(i) _(1,1) _(+12,s) ₁ _(i) _(1,1) _(+4,s) ₁ _(i) _(1,1)_(+12,s) ₂ _(i1,)

⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(+4,s) ₁ _(i) _(1,1) _(+12,s) ₁_(i) _(1,1) _(+4,s) ₂ _(i) _(1,2) ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1)_(+4,s) ₁ _(i) _(1,1) _(+12,s) ₁ _(i) _(1,1) _(+12,s) ₂ _(i) _(1,2) ⁽³⁾i_(2′) 12 13 14 15 Precoder W_(s) ₁ _(i) _(1,1) _(+6,s) ₁ _(i) _(1,1)_(+6,s) ₁ _(i) _(1,1) _(+14,s) ₂ _(i)

⁽³⁾ W_(s) ₁ _(i) _(1,1) _(+14,s) ₁ _(i) _(1,1) _(+6,s) ₁ _(i) _(1,1)_(+14,s) ₂ _(i1,)

⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(+6,s) ₁ _(i) _(1,1) _(+14,s) ₁_(i) _(1,1) _(+6,s) ₂ _(i) _(1,2) ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1)_(+6,s) ₁ _(i) _(1,1) _(+14,s) ₁ _(i) _(1,1) _(+14,s) ₂ _(i) _(1,2) ⁽³⁾i₂′ 16-31 Precoder Entries 16-31 constructed with replacing the fourthsubscript s₂i_(1,2) with s₂i_(1,2) + p₂ in entries 0-15.

indicates data missing or illegible when filed

In the Rel-10 8-Tx rank-4 codebook, rank-4 precoder codebook comprisesbeam groups with four pairs of orthogonal beams: (0,8), (2,10), (4,12),and (6,14). One orthogonal beam pair (b₀,b₁) is selected for the fourlayers and four precoders can be constructed with applying two co-phasematrices of

$\begin{bmatrix}1 & 1 & 1 & 1 \\1 & 1 & {- 1} & {- 1}\end{bmatrix}\mspace{14mu} {{and}\mspace{14mu}\begin{bmatrix}1 & 1 & 1 & 1 \\j & j & {- j} & {- j}\end{bmatrix}}$

on the tuple (b₀,b₁, b₀,b₁).

In some embodiments, TABLE 41 is used as a rank-4 (4 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein the corresponding rank 4 precoder is

$W_{m_{1},m_{1}^{\prime},m_{2},n}^{(4)} = {{\frac{1}{\sqrt{4Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}} & {\phi_{n}{v_{m_{1}^{\prime}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}^{\prime}} \otimes u_{m_{2}}}}\end{bmatrix}}.}$

Note that the master rank-4 codebook table is constructed based on thelegacy (Rel12 8-Tx) rank-4 orthogonal beam pairs for the longerdimension (L₁=4) for each of the beams in the shorter dimension (L₁=2).

The number of rank-4 i₂ indices in the master codebook in TABLE 41 is16, so 4 bits are needed to report i₂ based on this master codebook.

In one method, the codebook parameters in the first dimension are legacyparameters, i.e., s₁=8, p₁=1, and i_(1,1)=0-3. In another method, theyare non-legacy parameters. The parameters for the second dimension, s₂and p₂, in this table can be selected, e.g., according to TABLE 13, andit is assumed that (L₁, L₂)=(4, 2). Also, i_(1,2)=0,1, . . . ,

$\frac{N_{2}O_{2}}{s_{2}} - 1.$

TABLE 41 Master codebook for 4 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0 1 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₁ _(i) _(1,1) _(+8,s) ₂_(i) _(1,2) _(,0) ⁽⁴⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₁ _(i) _(1,1) _(+8,s) ₂_(i) _(1,2) _(,1) ⁽⁴⁾ W_(s) ₁ _(i) _(1,1) _(+2,s) ₁ _(i) _(1,1) _(+10,s)₂ _(i) _(1,2) _(,0) ⁽⁴⁾ W_(s) ₁ _(i) _(1,1) _(+2,s) ₁ _(i) _(1,1)_(+10,s) ₂ _(i) _(1,2) _(,1) ⁽⁴⁾ i_(2′) 4 5 6 7 Precoder W_(s) ₁ _(i)_(1,1) _(+4,s) ₁ _(i) _(1,1) _(+12,s) ₂ _(i) _(1,2) _(,0) ⁽⁴⁾ W_(s) ₁_(i) _(1,1) _(+4,s) ₁ _(i) _(1,1) _(+12,s) ₂ _(i) _(1,2) _(,1) ⁽⁴⁾ W_(s)₁ _(i) _(1,1) _(+6,s) ₁ _(i) _(1,1) _(+14,s) ₂ _(i) _(1,2) _(,0) ⁽⁴⁾W_(s) ₁ _(i) _(1,1) _(+6,s) ₁ _(i) _(1,1) _(+14,s) ₂ _(i) _(1,2) _(,1)⁽⁴⁾ i₂′ 8-15 Precoder Entries 8-15 constructed with replacing the secondsubscript s₂i_(1,2) with s₂i_(1,2) + p₂ in entries 0-7.

Embodiments on Rank-3 and Rank-4 Beam Grouping

FIG. 38 illustrates beam pairs 3800 to construct rank-3 and rank-4master codebooks according to some embodiments of the presentdisclosure. The embodiment shown in FIG. 387 is for illustration only.Other embodiments could be used without departing from the scope of thepresent disclosure.

Utilizing the legacy 4 (Rel12 8-Tx) orthogonal beam pairs for the longerdimension (L₁=4) and for each beam in the shorter dimension (L₂=2), an8×2 grid can be considered for the two dimensions as shown (shaded andpattern squares) in FIG. 38. There are four types of shaded and patternsquares corresponding to the four orthogonal beam pairs in the firstdimension. In the rest of the disclosure, we indicate the fourorthogonal beam pairs in a beam group by their leading beams {0,2,4,6}.When the beam combination indices (x, y) where x={0,2,4,6} and y={0,1}is selected for the 1^(st) and 2^(nd) dimensions, the orthogonal beampair with the leading beam x is selected for the longer dimension andthe beam index y is selected for the shorter dimension.

FIG. 39 illustrates grouping schemes 3900 for rank-3 and rank-4 i₂according to some embodiments of the present disclosure. The embodimentshown in FIG. 39 is for illustration only. Other embodiments could beused without departing from the scope of the present disclosure.

Depending on the values of parameters L₁ and L₂, subset restriction onrank-3 and rank-4 i₂ indices can be differently applied. In someembodiments, a beam grouping scheme is configured by means of codebooksubset selection or codebook subsampling on rank-3 and rank-4 i₂ e.g.,indices in terms of parameters L₁ and L₂, with an assumption that themaster codebook has rank-3 and rank-4 i₂ indices corresponding to 1210:(L₁, L₂)=(4,2). In this case, the master codebook for i₂ comprises 16rank-3 and 8 rank-4 beam combinations, which are constructed from the8×2 (shaded and pattern squares) beam combination grid where 8corresponds to the four orthogonal beam pairs for the first dimension(L₁=4) and 2 corresponds to the 2 beams for the second dimension (L₂=2).

In some embodiments, the 1^(st) dim and the 2^(nd) dim in the figurecorresponds to i_(2,1) and i_(2,2). The shaded or pattern squaresrepresent the rank-3 and rank-4 i₂ (or i_(2,1) and i_(2,2)) indices thatform a beam group and are obtained after subset restriction and thewhite squares represent the indices that are not included in the beamgroup. In the figure, only one half (i.e., leading beam indices{0,2,4,6} of the four orthogonal beam pairs) are shown. The second halfis identical to the first half.

As shown in FIG. 39, element 1220 corresponds to a codebook subset (or abeam group) when (L₁,L₂)=(4,1) is configured and the selected beamcombination comprises of 4 beam combinations located at {(x,0)} wherex={0,2,4,6} is the leading beam indices of the four orthogonal beampairs.

Beam grouping schemes 1230 a-1230 f correspond to a codebook subset (ora beam group) when (L₁,L₂)=(2,2) is configured and six different beamcombinations are applied. For instance:

in beam grouping scheme 1230 a, the 4 beam combinations are {(x,y)}where x={0,2}and y={0,1};

in beam grouping scheme 1230 b, the 4 beam combinations are {(x,y)}where x={0,4}and y={0,1};

in beam grouping scheme 1230 c, the 4 beam combinations are {(x,y)}where x={0,6}and y={0,1};

in beam grouping scheme 1230 d, the 4 beam combinations are {(x,0)}where x={0,4}and {(x,1)} where x={2,6};

in beam grouping scheme 1230 e, the 4 beam combinations are {(x,0)}where x={0,6}and {(x,1)} where x ={2,4}; and

in 1280 f, the 4 beam combinations are {(x,0)} where x={0,2}and {(x,1)}where x={4,6}.

Beam grouping schemes 1240 a-1240 d correspond to a codebook subset (ora beam group) when (L₁,L₂)=(1,2) is configured and four different beamcombinations are applied. For instance: in beam grouping scheme 1240 a,the 2 beam combinations {(0,0), (0,1)};

in beam grouping scheme 1240 b, the 2 beam combinations are {(0,0),(2,1)};

in beam grouping scheme 1240 c, the 2 beam combinations are {(0,0),(4,1)}; and

in beam grouping scheme 1240 d, the 2 beam combinations are {(0,0),(6,1)}.

Beam grouping schemes 1250 a-1250 c correspond to a codebook subset (ora beam group) when (L₁,L₂)=(2,1) is configured and three different beamcombinations are applied. For instance,

in beam grouping scheme 1250 a, the 2 beam combinations are {(x,0)}where x={0,2};

in beam grouping scheme 1250 b, the 2 beam combinations are {(x,0)}where x={0,4}; and

in beam grouping scheme 1250 c, the 2 beam combinations are {(x,0)}where x={0,6}.

Beam grouping scheme 1260 corresponds to a codebook subset (or a beamgroup) when (L₁,L₂)=(1,1) is configured and the one beam combination islocated at (0,0).

The number of rank 3-4 i₂ indices with the subset restriction depends onthe beam grouping schemes. For the beam grouping schemes 1220-1230, itis 16 and 8, respectively for rank 3 and 4. So, 4 bits and 3 bits areneeded to report i₂ for each configured beam grouping scheme from1220-1230 for rank-3 and rank-4, respectively. For the beam groupingschemes 1240-1250, it is 8 and 4, respectively for rank 3 and 4. So, 3bits and 2 bits are needed to report i₂ for each configured beamgrouping scheme from 1240-1240 for rank-3 and rank-4, respectively. Forthe beam grouping scheme 1260, it is 2 and 1, respectively for rank 3and 4. So, 1 bits and 0 bit are needed to report i₂ for the configuredbeam grouping scheme 1260 for rank-3 and rank-4, respectively.

In one method, for both dimensions, a UE can be configured with pair ofnumbers of beams in a beam group (i.e., (L₁, L₂)), so that the UE canrestrict the rank-3 and rank-4 beam combinations as illustrated in FIG.39. In one example, the UE is configured a beam group (i.e., (L₁, L₂))in the higher-layer according to TABLE 42. For (L₁, L₂)=(2,2), (1,2),and (2,1), there are multiple grouping schemes. In one option, one beamgrouping scheme out of multiple beam grouping schemes is explicitlyconfigured. In another option, it is fixed to default beam groupingschemes 1230 a, 1240 a, and 1250 a, for example.

TABLE 42 Rank-3 and rank-4 beam group configuration table ParametersCandidate values Number of beams (L₁, L₂) (4, 1), (2, 2), (1, 2), (2,1), (1, 1) (Respectively corresponding to 1220, 1230a, 1240a, 1250a. and1260)

In another method, a UE can be configured in the higher-layer (RRC) witha beam grouping scheme, selected among a subset of beam grouping schemes1220-1260 in FIG. 39. For example, the subset of beam grouping schemesis {1220, 1230 a, 1260} in FIG. 39, and the UE is configured with onebeam grouping scheme out of this subset.

In another method, a UE can report a beam grouping scheme, selectedamong a subset of beam grouping schemes 1220-1260 in FIG. 39. Forexample, the subset of beam grouping schemes is {{1220, 1230 a, 1260} inFIG. 39, and the UE reports one beam grouping scheme out of this subset.

Codebook Design for Ranks 5-8

In the Rel-12 8-Tx rank-5 codebook, the precoder codebook comprises beamgroups with an orthogonal beams (b₀, b₁, b₂)=(0,8,16) for rank 5 and 6and (b₀, b₁, b₂,b₃)=(0,8,16,24) for rank 7 and 8. The rank-5 and rank-6precoders can be constructed with applying the co-phase matrix of

$\begin{bmatrix}1 & 1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} & 1\end{bmatrix}\mspace{14mu} {{and}\mspace{14mu}\begin{bmatrix}1 & 1 & 1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} & 1 & {- 1}\end{bmatrix}}$

on the tuple (b₀, b₀, b₁,b₁, b₂) and (b₀, b₀, b₁,b₁, b₂, b₂),respectively. The rank 7 and rank 8 pre-coders are similarly constructedby including the fourth orthogonal beam 24.

In some embodiments, TABLE 43 is used as a rank-r (r layer) wherer={5,6,7,8} master codebook that can be used for any of Q=12, 16 and 32antenna configurations, wherein the corresponding rank-5 precoder is:

${W_{m_{1},m_{2}}^{(5)} = {\frac{1}{\sqrt{5Q}}\left\lbrack \begin{matrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}}\end{matrix} \right\rbrack}},$

the corresponding rank-6 precoder is:

${W_{m_{1},m_{2}}^{(6)} = {\frac{1}{\sqrt{6Q}}\left\lbrack \begin{matrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {{- v_{m_{1} + 16}} \otimes u_{m_{2}}}\end{matrix} \right\rbrack}},$

the corresponding rank-7 precoder is:

${W_{m_{1},m_{2}}^{(7)} = {\frac{1}{\sqrt{7Q}}\left\lbrack \begin{matrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {{- v_{m_{1} + 16}} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}}}\end{matrix} \right\rbrack}},$

and the corresponding rank-8 precoder is:

$W_{m_{1},m_{2}}^{(8)} = {{\frac{1}{\sqrt{8Q}}\left\lbrack \begin{matrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {{- v_{m_{1} + 16}} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}}} & {{- v_{m_{1} + 24}} \otimes u_{m_{2}}}\end{matrix} \right\rbrack}.}$

TABLE 43 Master codebook for r = {5, 6, 7, 8} layer CSI reporting for(L₁, L₂) = (4, 2) i₂ ^(′) 0 1 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) ^((r)) W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ ^((r))

Note that the master rank 5-8 codebook tables are constructed based onthe legacy (Rel12 8-Tx) rank 5-8 orthogonal beams for the longerdimension (L₁=4) for each of the beams in the shorter dimension (L₁=2).In one method, the codebook parameters in the first dimension are legacyparameters, i.e., s₁=2, p₁=1, and i_(1,1)=0-3 for rank 5-7 and i_(1,1)=0for rank 8. In another method, they are non-legacy parameters. Theparameters for the second dimension, s₂ and p₂, in this table can beselected, e.g., according to TABLE 13, and it is assumed that (L₁,L₂)=(4, 2). Also, i_(1,2)=0,1, . . . ,

$\frac{N_{2}O_{2}}{s_{2}} - 1.$

The number of rank 5-8 i₂ indices in the master codebook in TABLE 43 is2, so 1 bit is needed to report i₂ based on this master codebook.

Ranks 5-8 Beam Grouping

FIG. 40 illustrates beam pairs 4000 to construct rank 5-8 beamcombination master codebooks according to some embodiments of thepresent disclosure. The embodiment shown in FIG. 40 is for illustrationonly. Other embodiments could be used without departing from the scopeof the present disclosure.

Utilizing the legacy 3 (4) orthogonal beams (0,8,16) ((0,8,16,24)) forrank 5-6 (rank 7-8) for the longer dimension (L₁=4) and for each beam inthe shorter dimension (L₂=2), an 3×2 (4×2) grid can be considered forthe two dimensions as shown (shaded squares) in FIG. 40.

FIG. 41 illustrates grouping schemes 4100 for rank 5-8 i₂ according tosome embodiments of the present disclosure. The embodiment shown in FIG.41 is for illustration only. Other embodiments could be used withoutdeparting from the scope of the present disclosure.

Depending on the values of parameters L₁ and L₂, subset restriction onrank 5-8 i₂ indices can be applied. In the embodiments, a beam groupingscheme is configured by means of codebook subset selection or codebooksubsampling on rank 5-8 i₂ e.g., indices in terms of parameters L₁ andL₂, with an assumption that the master codebook has rank 5-8 i₂ indicescorresponding to 1410 (rank 5-6) and 1430 (rank 7-8): (L₁, L₂)=(4,2).The shaded (black) squares represent the rank 5-8 i₂ (or i_(2,1) andi_(2,2)) indices that form abeam group and are obtained after subsetrestriction and the white squares represent the indices that are notincluded in the beam group. As shown, 1420 and 1440 correspond to acodebook subset (or a beam group) when (L₁,L₂)=(4,1) is configured. Notethat no i₂ indication is needed whenever subset restriction isconfigured.

In some embodiments, the number of i₂ indices (W2 codebook size) of themaster codebook and the codebooks that are obtained according to the W2beam grouping schemes (or after codebook subset selection (CSS))according to some embodiments of this disclosure can be summarized as inTABLE 44. It can be observed that a reduction of 1 bit in W2 feedbackcan be achieved with the proposed W2 beam grouping scheme (or CSS)compared to the master codebook.

TABLE 44 Summary of the number of i₂ indices (W₂ codebook size) andnumber of bits to report i₂ Number of i₂ indices according Number of i₂to the proposed beam grouping schemes Number indices in master (or afterCSS) (number of bits) of W2 codebook (L₁, layers (number of bits) L₂) =(4, 2), (L₁, L₂) = (L₁, L₂) = (rank) (L₁, L₂) = (4, 2) (4, 1), or (2, 2)(1, 2) or (2, 1) (1, 1) 1 32 (5 bits) 16 (4 bits) 8 (3 bits)  4 (2 bits)2 32 (5 bits) 16 (4 bits) 8 (3 bits) 2 (1 bit) 3 32 (5 bits) 16 (4 bits)8 (3 bits) 2 (1 bit) 4 16 (4 bits)  8 (3 bits) 4 (2 bits) 1 (0 bit) 5-8 2 (1 bit)  1 (0 bit) 1 (0 bit)  1 (0 bit)

Embodiments on Different Beams in One or Both of the Longer and ShorterDimensions

In some embodiments, TABLE 44 is used to construct the beam pairs in theshorter dimension (L₂=2) for the rank-2 master codebook.

TABLE 45 Legacy 2-Tx rank-2 beam pairs for shorter dimension (L₂ = 2)Beam pair index 0 1 2 (first layer, second layer) (0, 0) (1, 1) (0, 1)

Rank-2 Codebook

In some embodiments, TABLE 46 is used as a rank-2 (2 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein TABLE 37 and TABLE 45, respectively are used forthe beam pairs in the longer and the shorter dimensions to construct themaster rank-2 codebook. The i₂ indices 0-31 are identical to those inTABLE 38 (i.e., rank-2 beam pair Type 1, and Type 2-1). In addition tothose, i₂ indices 32-47 are corresponding to rank-2 beam pair Type 2-2and 2-3.

It is noted that the number of rank-2 i₂ indices in the master codebookin TABLE 46 is 48.

TABLE 46 Master codebook for 2 layer CSI reporting for (L₁, L₂) = (4, 2)i₂ ^(′) 0-31 Entries 0-31 are identical to those in TABLE 38. i₂ ^(′) 3233 34 35 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ W_(s) ₁_(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,1) ⁽²⁾ i₂ ^(′) 36 37 38 39 W_(s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0)⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1)_(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1)⁽²⁾ i₂ ^(′) 40 41 42 43 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁_(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+2p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂ ^(′) 44 45 46 47 W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₃ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,) _(s) ₂ _(i) _(1,2)_(,) _(s) ₁ _(i) _(1,1) _(+p) ₃ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p)₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,1) ⁽²⁾

FIG. 42 illustrate a beam combination 4200 to construct a mastercodebook for rank-2 beam combinations according to TABLE 37 and TABLE 45according to embodiments of the present disclosure. The embodiment shownin FIG. 42 is for illustration only. Other embodiments could be usedwithout departing from the scope of the present disclosure.

Utilizing the 8 beam pairs in TABLE 37 for the longer dimension (L₁=4)and the 3 beam pairs in TABLE 45 for the shorter dimension (L₂=2), an8×3 grid can be considered for the two dimensions as shown in FIG. 42.When beam pair indices (x, y) is selected for the 1^(st) and 2^(nd)dimensions, corresponding beam pairs are selected for the longer and theshorter dimension, according to TABLE 37 and TABLE 45, respectively.

For example, applying TABLE 37 to x and TABLE 45 toy, with x=1 theselected beam pair for the first dimension is (1,1) and with y=2, theselected beam pair for the second dimension is (0,1). Then, thecorresponding rank-2 precoding matrix is:

${W_{m_{1},m_{2},m_{1}^{\prime},m_{2}^{\prime},n}^{(2)} = {\frac{1}{\sqrt{2Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}}}\end{bmatrix}}},$

where: m₁=m_(1′)=s₁·s₁·i_(1,1)+p₁; m₂=s₂·i_(1,2); andm_(2′)=s₂·i_(1,2)+p₂.

In general, when the selected beam pair for the first dimension is(a₀,a₁) and the selected beam pair for the second dimension is (b₀, b₁),the beam indices m₁, m_(1′), m₂, m_(2′) are selected as:m₁=s₁·i_(1,1)+a₀·p₁; m_(1′)=s₁·i_(1,1)+a₁·p₁; m₂=s₂·i_(1,2)+b₀·p₂; andm_(2′)=s₂·i_(1,2)+a₁·p₂.

As total number of pairs for (x,y) in FIG. 42 is 24, with applying thetwo co-phases of {1,j} for φ_(n), total number of codewords becomes 48.

Rank-2 Beam Groupings

FIG. 43 illustrates rank-2 beam grouping schemes 4300 according to someembodiments of the present disclosure. The embodiment shown in FIG. 43is for illustration only. Other embodiments could be used withoutdeparting from the scope of the present disclosure.

Depending on the values of parameters L₁ and L₂, subset restriction onrank-2 i₂ indices can be differently applied. In the embodiments, a beamgrouping scheme is configured by means of codebook subset selection orcodebook subsampling on rank-2 i₂ e.g., indices in terms of parametersL₁ and L₂, with an assumption that the master codebook has rank-2 i₂indices corresponding to 1610: (L₁, L₂)=(4,2). In this case, the mastercodebook for i₂ comprises 24 rank-2 beam combinations, as shown in FIG.43 also, which are shown as a 8×3 beam combination grid where 8corresponds to the number of legacy rank-2 beam pairs for the firstdimension (L₁=4, see TABLE 37) and 3 corresponds to the rank-2 beampairs for the second dimension (L₂=2, see TABLE 45).

In some embodiments, the 1^(st) dim and the 2^(nd) dim in the figurecorrespond to i_(2,1) and i_(2,2). The shaded (black) squares representthe rank-2 i₂ (or i_(2,1) and i_(2,2)) indices that form a beam groupand are obtained after subset restriction and the white squaresrepresent the indices that are not included in the beam group.

The number of rank-2 i₂ indices with the subset restriction depends onthe beam grouping schemes. For example, for the beam grouping schemeswith (L₁, L₂)=(4,1) and (2,2), it is 16, so 4 bits are needed to reporti₂, for each configured beam grouping scheme.

In one method, for both dimensions, a UE can be configured with pair ofnumbers of beams in a beam group (i.e., (L₁, L₂)), so that the UE canrestrict the rank-2 beam combinations as illustrated in FIG. 43 16 Inone example, the UE is configured a beam group (i.e., (L₁, L₂)) in thehigher-layer according to a configuration table. For (L₁, L₂)=(2,2),(2,1), and (1,2), there are multiple beam groups. In one option, onebeam group out of multiple beam groups is explicitly configured. Inanother option, it is fixed to a default beam group.

In another method, a UE can be configured in the higher-layer (RRC) witha beam grouping scheme, selected among a subset of beam grouping schemesin FIG. 43.

In another method, a UE can report a beam grouping scheme, selectedamong a subset of beam grouping schemes in FIG. 43.

In some embodiments, the beam grouping (or subset restriction) isapplied based on the configured rank-2 beam pair type. For instance, theUE may be configured by the higher layer signaling about the rank-2 beampair type according to TABLE 47.

TABLE 47 Rank-2 beam pair type configuration table Configuration Rank-2beam pair type 0-4 Type 1, (Type 1, Type 2-1), (Type 1, Type 2-2), (Type1, Type 2-1,Type 2-2), (Type 1, Type 2-1, Type 2-2, Type 2-3),

In some embodiments, the beam grouping (or subset restriction) isapplied based on the dimension indicator I for different beams for thetwo layers. For instance, the UE is configured by the higher layersignaling about the dimension indicator I for different beams for thetwo layers according to TABLE 48, where I={0} indicates the same beamfor the two layers is configured in both dimensions.

TABLE 48 Dimension for different beam configuration table ConfigurationDimension indicator for different beam I 0-3 {0}, {1}, {2}, {1, 2}

Rank 3-4 Codebook

TABLE 49 and TABLE 50 are used as a rank-3 and rank-4 master codebookthat can be used for any of Q=12, 16 and 32 antenna configurations,wherein TABLE 45 is used for the beam pairs in the shorter dimension toconstruct the master codebook. In rank-3 codebook, the i₂ indices 0-31are identical to those in TABLE 40. In addition to those, i₂ indices32-47 are corresponding to the different beam pair (0,1) in the shorterdimension (L₂=2). The rank-4 table is constructed similarly.

Note that the number of i₂ indices in the rank-3 master codebook inTABLE 49 is 48, and that in the rank-4 master codebook is 24.

TABLE 49 Master codebook for 3 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0-31 Precoder Entries 0-31 are identical to those in TABLE 40. i₂′32-47 Precoder Entries 32-47 constructed with replacing the secondsubscript s₂i_(1,2) with s₂i_(1,2) + p₂ in entries 0-15.

TABLE 50 Master codebook for 4 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0-15 Precoder Entries 0-15 are identical to those in TABLE 41. i₂′16-23 Precoder Entries 16-23 constructed with replacing the secondsubscript s₂i_(1,2) with s₂i_(1,2) + p₂ in entries 0-7.

Rank-3 and Rank-4 Beam Groupings

FIG. 44 illustrates beam grouping schemes 4400 for rank-3 and rank-4 i₂according to embodiments of the present disclosure. The embodimentsshown in FIG. 44 are for illustration only. Other embodiments could beused without departing from the scope of the present disclosure.

Depending on the values of parameters L₁ and L₂, subset restriction onrank-3 and rank-4 i₂ indices can be differently applied. In theembodiments, a beam grouping scheme is configured by means ofillustrates codebook subset selection or codebook subsampling on rank-3and rank-4 i₂ e.g., indices in terms of parameters L₁ and L₂, with anassumption that the master codebook has rank-3 and rank-4 i₂ indicescorresponding to 1710: (L₁, L₂)=(4,2). The shaded and pattern squaresrepresent the i₂ (or i_(2,1) and i_(2,2)) indices that form a beam groupand are obtained after subset restriction and the white squaresrepresent the indices that are not included in the beam group.

The number of rank 3-4 i₂ indices with the subset restriction depends onthe beam grouping schemes. For example, for the beam grouping schemeswith (L₁, L₂)=(4,1) and (2,2), the number of rank-3 (rank-4) i₂ indiceswith the subset restriction is 16 (8), so 4 bits (3 bits) are needed toreport i₂, for each configured beam grouping scheme.

In one method, for both dimensions, a UE can be configured with pair ofnumbers of beams in a beam group (i.e., (L₁, L₂)), so that the UE canrestrict the rank-3 and rank-4 beam combinations as illustrated in FIG.44. In one example, the UE is configured a beam group (i.e., (L₁, L₂))in the higher-layer according to a configuration table. For (L₁,L₂)=(2,2), (1,2) and (2,1), there are multiple beam combinations. In oneoption, one beam combination out of multiple beam combinations isexplicitly configured. In another option, it is fixed to a default beamcombination.

In another method, a UE can be configured in the higher-layer (RRC) witha beam grouping scheme, selected among a subset of beam grouping schemesin FIG. 44 17.

In another method, a UE can report a beam grouping scheme, selectedamong a subset of beam grouping schemes in FIG. 44.

Rank 5-8 Codebook

In some embodiments, TABLE 51 is used as a rank-r (r layer) wherer={5,6,7,8} master codebook that can be used for any of Q=12, 16 and 32antenna configurations, wherein TABLE 45 is used for the beam pairs inthe shorter dimension to construct the master codebook and thecorresponding rank 5 precoder is:

${W_{m_{1},m_{2},m_{2}^{\prime},m_{2}^{''}}^{(5)} = {\frac{1}{\sqrt{5Q}}\left\lbrack \begin{matrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{''}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}^{''}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}}\end{matrix} \right\rbrack}},$

the corresponding rank 6 precoder is:

${W_{m_{1},m_{2},m_{2}^{\prime},m_{2}^{''}}^{(6)} = {\frac{1}{\sqrt{6Q}}\left\lbrack \begin{matrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{''}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}^{''}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {{- v_{m_{1} + 16}} \otimes u_{m_{2}}}\end{matrix} \right\rbrack}},$

the corresponding rank 7 precoder is:

${W_{m_{1},m_{2},m_{2}^{\prime},m_{2}^{''}} = {\frac{1}{\sqrt{7\; Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}^{\prime}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{''}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}^{''}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {{- v_{m_{1} + 16}} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}^{''}}}\end{bmatrix}}},$

and the corresponding rank 8 precoder is:

$W_{m_{1},m_{2},m_{2}^{\prime},m_{2}^{''}}^{(8)} = {\frac{1}{\sqrt{8\; Q}}{\quad{\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1} + 24} \otimes u_{m_{2}^{\prime}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1} + 8} \otimes u_{m_{2}^{''}}} & {{- v_{m_{1} + 8}} \otimes u_{m_{2}^{''}}} & {v_{m_{1} + 16} \otimes u_{m_{2}}} & {{- v_{m_{1} + 16}} \otimes u_{m_{2}}} & {v_{m_{1} + 24} \otimes u_{m_{2}^{''}}} & {{- v_{m_{1} + 24}} \otimes u_{m_{2}^{''}}}\end{bmatrix},}}}$

TABLE 51 Master codebook for r = {5, 6, 7, 8} layer CSI reporting for(L₁, L₂) = (4, 2) i ₂ ^(′) 0 1 2 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(,s) ₂ _(i) _(1,2) _(,s) ₂ _(i) _(1,2) ^((r)) W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₂ _(i)_(1,2) _(+p) ₂ ^((r)) W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₂_(i) _(1,2) _(,s) ₂ _(i) _(1,2) _(+p) ₂ ^((r))

Note that the master rank 5-8 codebook tables are constructed based onthe legacy (Rel 12 8-Tx) rank 5-8 orthogonal beams for the longerdimension (L₁=4). The i₂ indices 0-1 are identical to those in TABLE 43.In addition to those, i₂=2 corresponds to the different beam pair (0,1)in the shorter dimension (L₂=2).

In one method, the codebook parameters in the first dimension are legacyparameters, i.e., s₁=2, p₁=1, and i_(1,1)=0-3 for rank 5-7 and i_(1,1)=0for rank 8. In another method, they are non-legacy parameters. Theparameters for the second dimension, s₂ and p₂, in this table can beselected, e.g., according to TABLE 13, and it is assumed that (L₁,L₂)=(4, 2). Also, i_(1,2)=0,1, . . . ,

$\frac{N_{2}O_{2}}{s_{2}} - 1.$

The number of rank 5-8 i₂ indices in the master codebook in TABLE 43 is3, so 2 bit is needed to report i₂ based on this master codebook.

Embodiments on Rank 5-8 Beam Groupings

FIG. 45 illustrates a beam combination 4500 to construct ranks 5-8master codebooks according to some embodiments of the presentdisclosure. The embodiment shown in FIG. 45 is for illustration only.Other embodiments could be used without departing from the scope of thepresent disclosure.

Utilizing the legacy 3 (4) orthogonal beams (0,8,16) ((0,8,16,24)) forranks 5-6 (rank 7-8) for the longer dimension (L₁=4) and for each beampair in TABLE 45 for the shorter dimension (L₂=2), an 3×3 (4×3) grid canbe considered for the two dimensions as shown (black squares) in FIG.45.

FIG. 46 illustrates beam grouping schemes for ranks 5-8 i₂ indicesaccording to the embodiments of the present disclosure. The embodimentshown in FIG. 46 is for illustration only. Other embodiments could beused without departing from the scope of the present disclosure.

Depending on the values of parameters L₁ and L₂, subset restriction onrank 5-8 i₂ indices can be applied. In the embodiments, a beam groupingscheme is configured by means of codebook subset selection or codebooksubsampling on rank 5-8 i₂ e.g., indices in terms of parameters L₁ andL₂, with an assumption that the master codebook has rank 5-8 i₂ indicescorresponding to 1910 (rank 5-6) and 1950 (rank 7-8): (L₁, L₂)=(4,2).The shaded (black) squares represent the rank 5-8 i₂ (or i_(2,1) andi_(2,2)) indices that form abeam group and are obtained after subsetrestriction and the white squares represent the indices that are notincluded in the beam group. As shown, 1920 and 1960 correspond to acodebook subset (or a beam group) when (L₁,L₂)=(4,1) is configured, 1930and 1970 correspond to a codebook subset (or a beam group) when(L₁,L₂)=(2,2) is configured and beam pair (0,0) and (1,1) are usedalternatively in the shorter dimension, and 1940 and 1980 correspond toa codebook subset (or a beam group) when (L₁,L₂)=(2,2) is configured andbeam pair (0,0) and (0,1) are used alternatively in the shorterdimension. Note that no i₂ indication is needed whenever subsetrestriction is configured.

Alternate Codebook Design

In order to keep the size of the master codebook in powers of 2, wepropose an alternate codebook design alternative in which: onlyimportant beam grouping schemes are considered; and the number ofredundant codewords in the master codebook (codewords that are notconfigured by any of the beam grouping schemes) is minimized.

In this alternate design, the rank-1 codebook is the same as in TABLE35. So, we focus on rank 2-8 codebook design. Also, in the following, wefocus on beam grouping schemes with (L₁,L₂)=(4,1) and (2,2). However,the design is applicable to other beam grouping schemes including(L₁,L₂)=(1,2), (2,1), and (1,1).

Rank 2 Codebook

In some embodiments, TABLE 52 is used to construct the beam pairs in theshorter dimension (L₂=2) for the rank-2 codebook.

TABLE 52 Rank-2 beam pairs in shorter dimension (2 beams) Beam pairindex 0 1 2 3 (first layer, second layer) (0, 0) (1, 1) (0, 1) (1, 0)

In some embodiments, TABLE 54 is used as a rank-2 (2 layer) mastercodebook that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein TABLE 37 and TABLE 52, respectively are used forthe beam pairs in the longer and the shorter dimension to construct themaster rank-2 codebook. The details of the i₂ indices to beam pairmappings are shown in TABLE53.

According to the TABLE 53, the i₂ indices 0-15 are identical to those inTABLE 38 which correspond to Rel12 8-Tx rank-2 beam pairs for the longerdimension and the beam pair index 0 (TABLE 52) for the shorterdimension. The i₂ indices 16-27 correspond to Rel12 8-Tx rank-2 beampair indices {0,1,3,4,5,7} (TABLE 37) for the longer dimension and thebeam pair index 1 (TABLE 52) for the shorter dimension. And there arethree options, i.e., Option 1-3, for the i₂ indices 28-31, which areshown in the table. The details of the three options are provided below.

TABLE 53 Rank 2 i₂ to beam pair mapping two dimensions (according toTABLES 37 and 52) i₂′ Rank 2: Option 1 Rank 2: Option 2 Rank 2: Option 3 0-15 {(x, 0)} for x = {0-7} 16-27 {(x, 1)} for x = {0, 1, 3, 4, 5, 7}28-29 (0, 2) (0, 2) (4, 2) 30-31 (4, 3) (1, 2) (4, 3)

Note that the number of rank-2 i₂ indices in the master codebook inTABLE 54 is 32.

TABLE 54 Master codebook for 2 layer CSI reporting for (L₁, L₂) = (4, 2)i₂ ^(′) 0-15 Entries 0-15 are identical to those in TABLE 38. i₂ ^(′) 1617 18 19 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂ ^(′) 20 21 22 23 W_(s) ₁ _(i)_(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+3p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s)₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂ ^(′) 24 25 26 27 W_(s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁_(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂ ^(′) 28 29 30 31Option 1 and 2: Option 1 and 2: Option 1 and 3: Option 1 and 3: W_(s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ Option 3: Option 3: Option2: Option 2: W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s)₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,1) ⁽²⁾

Rank-2 Beam Grouping Scheme

FIG. 47 illustrates beam grouping scheme or codebook subset selection4700 on rank-2 i₂ indices in terms of parameters L₁ and L₂, with anassumption that the master codebook has rank-2 i₂ indices correspondingto (L₁, L₂)=(4,2) and TABLE 54, according to the embodiments of thepresent disclosure.

In this case, the master codebook for i₂ comprises 16 rank-2 beam paircombinations, as shown in FIG. 47, which are shown as a shaded andpattern squares in the 2D grid (x,y), where the first component xcorresponds to the legacy Rel12 8-Tx based rank-2 beam pairs for thefirst dimension (L₁=4, see TABLE 37) and the second component ycorresponds to the beam pairs for the second dimension (L₂=2) accordingto TABLE 52. The shaded and pattern squares represent the rank-2 i₂ (ori_(2,1) and i_(2,2)) indices that are obtained based on the beamgrouping scheme or after subset restriction from the master codebook andthe white squares represent the indices that are redundant and are hencenot included in the master codebook.

As shown, there are three beam grouping schemes (or CSS methods), namelybeam group 0-beam group 2. Beam group 0 corresponds to a codebook subset(or beam group) when (L₁,L₂)=(4,1) is configured and the selected beamcombination comprises of 8 combinations located at{(x,0)} where x isaccording to TABLE 37.

Beam group 1 corresponds to a codebook subset (or beam group) when(L₁,L₂)=(2,2) is configured and depending on how rank-2 beamcombinations are formed out of the fours beams {(x,y)} where x,y={0,1},there are following three options for Beam group 1:

Option 1: In this option, the four beams (0,0), (0,1), (1,1), and (1,0)are first numbered as 0,1,2, and 3 respectively, and then legacy 8-Txrank-2 beam pairs are formed according to TABLE 37;

Option 2: In this option, the legacy 2-Tx rank-2 beam pairs (0,0),(1,1), and (0,1) are considered in one dimension d={1,2}, and the samebeam pair (0,0) and (1,1) are considered in the other dimension; and

Option 3: In this option, 2 diagonal beam pairs corresponding to{(0,0),(1,1)} and {(0,1),(1,0)}, and 2 horizontal (or first or longerdimension) beam pairs corresponding to {(0,0),(0,1)} and {(1,0),(1,1)}beam pairs are considered.

Beam group 2 corresponds to a codebook subset (or beam group) when(L₁,L₂)=(2,2) is configured and the configured beam pairs follow thecheck (cross) pattern as shown in the figure.

The number of rank-2 i₂ indices with the subset restriction according tothree beam grouping scheme is 16, so 4 bits are needed to report i₂ forthe configured beam grouping scheme.

FIG. 47 illstrates alternate rank 1 and rank 2 codebook designs (bothrank 1 and rank 2 codebook size=32) according to the present disclosure.The embodiment shown in FIG. 47 is for illustration only. Otherembodiments could be used without departing from the scope of thepresent disclosure.

In one method, for both dimensions, a UE can be configured with the beamgrouping scheme or CSS method (or a pair of numbers of beams in a beamgroup, i.e., (L₁, L₂)), so that the UE can restrict the rank-2 beamcombinations as illustrated in FIG. 47. In one example, the UE isconfigured a beam grouping scheme or CSS method in the higher-layeraccording to TABLE 55. For Beam group 1, either one of Option 1, Option2, and Option 3 is explicitly configured or one of the three is adefault option (for example Option 1).

TABLE 55 Rank-2 beam combination configuration table RRC ConfigurationCandidates {0, 1, 2} {Beam group 0, Beam group 1, Beam group 2}

In another method, a UE can be configured in the higher-layer (RRC) witha beam grouping scheme, selected from Beam group 0, Beam group 1 (Option1), Beam group (Option 2), Beam group 1 (Option 3), and Beam group 2.

In another method, a UE can report a beam grouping scheme, selected fromBeam group 0, Beam group 1 (Option 1), Beam group 1 (Option 2), Beamgroup 1 (Option 3), and Beam group 2.

In some embodiments, the master rank-2 codebook comprises of beam pairscorresponding to all of Beam group 0, Beam group 1 (Option 1), Beamgroup 1 (Option 2), Beam group 1 (Option 3), and Beam group 2. Thecorresponding rank-2 table is shown in TABLE 56. Note that in this matercodebook, the number of i₂ indices is 36. In one method, one rank-2 beamgroup out of five beam groups can be configured to a UE using thistable.

Similar master rank-2 tables for other beam grouping schemes accordingto some embodiments of this disclosure can be constructed similarly.

TABLE 56 Master codebook for 2 layer CSI reporting for (L₁, L₂) = (4, 2)i₂ ^(′) 0-27 Entries 0-27 are identical to those in TABLE 54. i₂ ^(′) 2829 30 31 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ W_(s) ₁_(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,1) ⁽²⁾ i₂ ^(′) 32 33 34 35 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾

In some embodiments, the master rank-2 codebook comprises of all thebeam pairs described in TABLE 56, and it additionally comprises two morecodewords with co-phase n=2, 3. The corresponding rank-2 table is shownin TABLE 57. Note that in this mater codebook, the number of i₂ indicesis 38. In one method, one rank-2 beam group out of five beam groups canbe configured to a UE using this table.

TABLE 57 Master codebook for 2 layer CSI reporting for (L₁, L₂) = (4, 2)i₂ ^(′) 0-35 Precoder Entries 0-35 are identical to those in TABLE 56.i₂ ^(′) 36 37 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾

Ranks 3-4 Codebook

FIG. 48 illustrates rank 3 and rank 4 beam grouping schemes 4800according to embodiments of the present disclosure. The embodiment shownin FIG. 48 is for illustration only. Other embodiments could be usedwithout departing from the scope of the present disclosure.

A beam grouping scheme (or CSS method) is configured from Beam group0-Beam group 2. And, the master rank 3 and rank 4 codebooks are as inTABLE 40 and TABLE 41, respectively.

Note that four orthogonal beam pairs {(0,8),(2,10),(4,12),(6,14)} in thefirst dimension are shown as shaded and pattern squares. The four beamsin three beam groups are numbered 0-3 as shown in the figure, and thecorresponding 2D beam pairs are tabulated TABLE 58.

TABLE 58 2D Beam Index Mapping for rank-3 and rank-4 CSS Beam Beam group0 (Beam Beam group 1 (Beam group 2 (Beam Index Pairs) Pairs) Pairs) 0(0, 0), (8, 0)  (0, 0), (8, 0)  (0, 0), (8, 0)  1 (2, 0), (10, 0) (0,1), (8, 1)  (2, 1), (10, 1) 2 (4, 0), (12, 0) (2, 1), (10, 1) (4, 0),(12, 0) 3 (6, 0), (14, 0) (2, 0), (10, 0) (6, 1), (14, 1)

Rank 3-4 codebooks corresponding to the case in which we have differentbeams (0,1) and (1,0) in the shorter dimension, according to TABLE 45and TABLE 52 can be constructed similarly.

Ranks 5-8 Codebook

FIG. 49 illustrates ranks 5 to 8 beam grouping schemes 4900 according tothe present disclosure. The embodiment shown in FIG. 49 is forillustration only. Other embodiments could be used without departingfrom the scope of the present disclosure.

The beam grouping scheme (or CSS method) is configured from Beam group 0and Beam group 2.

The master rank 5-8 codebooks are as in TABLE 43, Note that fourorthogonal beam pairs {(0,8),(2,10),(4,12),(6,14)} in the firstdimension are shown as shaded and pattern squares. The four beams inBeam group 0 and Beam group 2 are numbered 0-3 as shown in the figure,and the corresponding 2D beam pairs are tabulated in TABLE 59.

TABLE 59 2D Beam index mapping for rank 5-8 CSS Index Beam group 0 (BeamPairs) Beam group 2 (Beam Pairs) 0 (0, 0), (8, 0), (16, 0) (0, 0), (8,0), (16, 0), (24, 0) 1 (0, 0), (8, 1), (16, 0) (0, 0), (8, 1), (16, 0),(24, 1)

Rank 5-8 codebooks corresponding to the case in which we have differentbeams (0,1) and (1,0) in the shorter dimension, according to TABLE 45and TABLE 52 can be constructed similarly.

Bitmap to Configure a Beam Grouping Scheme or CSS

In some embodiments, the beam grouping scheme for each rank 1-8codebooks may be configured based on a bitmap, where the length of thebitmap equals to number of beam combinations (for a given rank) in themaster codebook.

For example, the beam grouping scheme for rank-1 codebook may beconfigured based on a bitmap of length K₁×K₂ (product of number ofrank-1 beams in two dimensions), where K_(d) with d=1,2 corresponds tothe number of beams in dimension d of the rank-1 master beam group(L₁,L⁻²). For instance, for the master beam group (L₁,L₂)=(4,2), K₁=L₁and K₂=L₂, so the length of bitmap is 8.

For example, the beam grouping scheme for rank-2 codebook may beconfigured based on a bitmap of length K₁×K₂ (product of number ofrank-2 beam pairs in two dimensions), where K_(d) with d=1,2 correspondsto the number of beam pairs in dimension d of the rank-2 master beamgroup (L₁,L₂). For instance, for the master beam group (L₁,L₂)=(4,2),K₁=8 (TABLE 35) and K₂=4 (TABLE 52), so the length of bitmap is 32.

The length of bitmaps for rank 3-8 codebooks can be determinedsimilarly.

An example of bitmaps for rank-1 and rank-2 beam grouping schemes inFIG. 47 is shown in TABLE 60 and TABLE 61, respectively.

In TABLE 60, the first column corresponds to the beam indices for 1^(st)and 2^(nd) dimensions in (L₁,L₂)=(4,2) grid of the master codebook. Thebitmaps corresponding to the three beam groups, Beam group 0-Beam group2 are shown in columns 2-4, where 1 indicates the corresponding beam inthe 2D grid is included in the beam group and 0 indicates otherwise.

In TABLE 61, the first column corresponds to the rank-2 beam pairindices for 1^(st) and 2^(nd) dimensions in (L₁,L₂)=(4,2) grid of themaster codebook. For example, the beam pair indices (1,0) indicates thebeam pair 1 from TABLE 37 for the 1^(st) dimension, and the beam pair 0from the TABLE 52 for the 2^(nd) dimension. The bitmaps corresponding tothe five rank-2 beam groups, Beam group 0, Beam group 1 (Option 1), Beamgroup 1 (Option 2), Beam group 1 (Option 3), and Beam group 2 are shownin columns 2-6, where 1 indicates the corresponding beam pair indices inthe 2D grid is included in the rank-2 beam group and 0 indicatesotherwise.

TABLE 60 Bitmap for rank-1 beam grouping schemes in FIG. 47 Beam indicesBitmaps (1^(st) sim, 2^(nd) dim) Beam group 0 Beam group 1 Beam group 2(0, 0) 1 1 1 (1, 0) 1 1 0 (2, 0) 1 0 1 (3, 0) 1 0 0 (0, 1) 0 1 0 (1, 1)0 1 1 (2, 1) 0 0 0 (3, 1) 0 0 1

TABLE 61 Bitmap for rank-2 beam grouping schemes in FIG. 47 Bitmaps Beampair indices Beam group Beam group Beam group Beam (1^(st) dim, 2^(nd)dim) Beam group 0 1 (Option 1) 1 (Option 2) 1 (Option 3) group 2 (0, 0)1 1 1 1 1 (1, 0) 1 1 1 1 0 (2, 0) 1 0 0 0 1 (3, 0) 1 0 0 0 0 (4, 0) 1 11 1 1 (5, 0) 1 0 0 0 0 (6, 0) 1 0 0 0 1 (7, 0) 1 0 0 0 0 (0, 1) 0 1 1 10 (1, 1) 0 1 1 1 1 (2, 1) 0 0 0 0 0 (3, 1) 0 0 0 0 1 (4, 1) 0 1 1 1 0(5, 1) 0 0 0 0 1 (6, 1) 0 0 0 0 0 (7, 1) 0 0 0 0 1 (0, 2) 0 1 1 0 0 (1,2) 0 0 1 0 0 (2, 2) 0 0 0 0 0 (3, 2) 0 0 0 0 0 (4, 2) 0 0 0 1 0 (5, 2) 00 0 0 0 (6, 2) 0 0 0 0 0 (7, 2) 0 0 0 0 0 (4, 3) 0 1 0 1 0 (5, 3) 0 0 00 0 (6, 3) 0 0 0 0 0 (7, 3) 0 0 0 0 0

In one alternative, bitmap for each rank can be configured separately.In another alternative, a composite bitmap obtained by concatenatingbitmaps for all ranks are formed and bitmaps for all ranks areconfigured jointly using the composite bitmap. In yet anotheralternative, multiple composite bitmaps are formed based on ranks andthey are configured separately. For example, rank 1-2 form one compositebitmap, rank 3-4 form another composite bitmap, and rank 5-8 formanother composite bitmap, and at least one of the three compositebitmaps is configured.

In one method, the bitmap can be configured using RRC.

In some embodiments, the number of 1's in the bitmap is fixed to a valuefor each rank 1-8.

For example, the number of 1's may be fixed to 4 for rank-1, and 8 forrank 2-4, and so on. In this example, the configured beam groupingschemes correspond to (L₁,L₂)=(4,1) or (2,2).

In another example, the number of 1's may be fixed to 2 for rank-1, and4 for rank 2-4, and so on. In this example, the configured beam groupingschemes correspond to (L₁,L₂)=(2,1) or (1,2).

In another example, the number of 1's may be fixed to 1 for rank 1-4. Inthis example, the configured beam grouping scheme corresponds to(L₁,L₂)=(1,1).

In some embodiments, the number of 1's in the bitmap is fixed tomultiple values for each rank 1-8.

For example, the number of 1's may be fixed to {1,4} for rank-1, and{1,8} for rank 2-4. In this example, the configured beam groupingschemes correspond to (L₁,L₂)=(4,1) or (2,2) or (1,1).

In some embodiments, for each rank, a beam grouping scheme can beconfigured (e.g., based on a bitmap or a beam grouping schemeindicator).

When a bitmap based approach is used, the length of the bitmap equals tothe number of i′₂ indices in the master codebook.

Examples of beam grouping scheme indication for rank-1 and rank-2 i′₂are shown in TABLE 62 and TABLE 63, respectively based upon TABLE 35 andTABLE 56.

TABLE 62 shows selected rank-1 i′₂ indices determined dependent upon aselected beam group. The selected indices can also be represented by abitmap.

TABLE 62 Selected i₂′ for rank-1 CSI reporting (in TABLE 35) Selectedi₂′ i₂′ Bitmap for selected i2 indices indices indices Bit 0-3 Bit 4-7Bit 8-11 Bit 12-15 Bit 16-19 Bit 20-23 Bit 24-27 Bit 28-31 Beam 0-15 1 11 1 0 0 0 0 group 0 Beam 0-7, 1 1 0 0 1 1 0 0 group 1 16-23 Beam 0-3, 10 1 0 0 1 0 1 group 2 8-11, 20-23, 28-31 Beam 0-3 1 0 0 0 0 0 0 0 group3

TABLE 63 shows selected rank-2 i′₂ indices determined dependent upon aselected beam group. Beam group 1 options 1, 2 and 3 are constructedaccording to FIG. 47.

TABLE 63 Selected i₂′ for rank-2 CSI reporting (in TABLE 56 and TALBLE57) i₂′ indices Selected i₂′ indices Beam group 0 0-15 Beam group 1(Option 1) 0-3, 8-9, 16-19, 22-23, 28-29, 34-35 Beam group 1 (Option 2)0-3, 8-9, 16-19, 22-23, 28-31 Beam group 1 (Option 3) 0-3, 8-9, 16-19,22-23, 32-35 Beam group 2 0-1, 4-5, 6-7, 12-13, 18-21, 24-27 Beam group3 (according to 0-1  TABLE 56) Beam group 3 (according to 0-1, 36-37TABLE 57)

Mapping i′₂ Indices into the Second PMI indices i₂

In some embodiments, the reported second PMI i₂ by the UE spans 0-A, andare one-to-one mapped sequentially from the selected i′₂ indices (e.g.,according to TABLE 61 for rank-1). Example values for A=1, 3, 7, 15, 31,63.

For example, when beam group 1 is selected for rank-1, the selected i′₂indices 0-7 and 16-23 are sequentially one-to-one mapped to i₂ indices0-15.

Fixed Codebooks

In some embodiments, the codebooks for some of or all ranks 1-8 for eachof 12, 16 and 32 antenna ports are fixed and no configuration isnecessary.

In one example, such fixed codebooks are the master codebooks of rank1-8 according to some embodiments of this disclosure.

In another example, such fixed codebooks are the codebooks of rank 1-8corresponding to the beam grouping (L₁,L₂)=(4,1) according to someembodiments of this disclosure.

In another example, such fixed codebooks are the codebooks of rank 1-8corresponding to the beam grouping (L₁,L₂)=(2,2) according to someembodiments of this disclosure.

In some embodiments, the codebooks for some of or all ranks 1-8 for eachof 12, 16 and 32 antenna ports are fixed depending on the antenna portconfigurations. For example, for 16 ports, codebooks are fixed fordepending on (N₁, N₂)=(1,8), (4,2), (2,4), and (8,1). The exact codebookis configured by configuring the antenna port configuration (N₁, N₂).

Note that the embodiments of this disclosure is applicable to other beamgroup sizes of the master codebook including (L₁,L₂)=(4,4).

Rank Specific Beam Grouping Scheme

In some embodiments, the configured beam grouping scheme is the same forall ranks 1-8. For example, the configured beam grouping schemecorresponds to one of multiple options for (L₁,L₂)=(2,2) for all ranks1-8, where the beam grouping scheme is according to some embodiments ofthis disclosure.

In some embodiments, the configured beam grouping scheme is specific toeach rank 1-8. For example, for rank-1, the configured beam groupingscheme may correspond to (L₁,L₂)=(4,1), and for rank-2, it maycorrespond to one of multiple options for (L₁,L₂)=(2,2), and so on,where the beam grouping scheme is according to some embodiments of thisdisclosure.

In some embodiments, the configured beam grouping scheme is specific toa fixed subset of ranks from 1-8. For example, for rank1-2, theconfigured beam grouping scheme may correspond to (L₁,L₂)=(2,2), and forrank 3-8, it may correspond to (L₁,L₂)=(4,1), where the beam groupingscheme is according to some embodiments of this disclosure.

In some embodiments, there are multiple different alternatives to decidewhether the beam grouping scheme is the same for all ranks, specific toeach rank, or specific to a subset of ranks. In one alternative, thebeam grouping schemes for different ranks are pre-determined. In anotheralternative, this decision is made at eNB. In another alternative, UEindicates this to the eNB.

Separate Master Codebook for Config A and B in FIG. 5 (Without TransposeAntenna Port Indexing)

If the antenna port configuration is explicitly configured, anddifferent (master) codebook is configured depending on the configuredantenna port, then we may have the following alternatives for codebookdesign.

Alternative 1: one codebook for both N₁≧N₂ (config A) and N₁<N₂ (configB) for symmetric antenna port layouts

This alternative is applicable to antenna port configurations (N₁,N₂)that are symmetric in the sense that the corresponding antenna portlayouts are transpose of one another. For example (N₁,N₂)=(2,4) and(4,2) for 16 port and (N₁,N₂)=(2,3) and (3,2) as shown in FIGS. 5A to5B. For such antenna port layouts, we may have the same codebook table,representing the different pre-coding vectors and matrices in the twolayouts.

In some embodiments, there is one (master) codebook table for both ofthe symmetric antenna port configurations. In this case, we canrepresent the two symmetric port configurations as N₁≧N₂ (config A) andN₁<N₂ (config B), for example config A and B in FIGS. 5A to 5B. However,depending on the configured antenna port configuration, the pre-coder isderived differently.

In one method, the order in which the Kronecker product is performed isdependent on the configuration. For instance, for the configuration inwhich N₁≧N₂, the UE derives the rank-1 pre-coder as

${W_{m_{1},m_{2},n}^{(1)} = {\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}},$

and for the configuration in which N₁<N₂, the UE derives the rank-1pre-coder as

$W_{m_{1},m_{2},n}^{(1)} = {{\frac{1}{\sqrt{Q}}\begin{bmatrix}{u_{m_{2}} \otimes v_{m_{1}}} \\{\phi_{n}{u_{m_{2}} \otimes v_{m_{1}}}}\end{bmatrix}}.}$

Note that the orders in which the Kronecker product is performed in thetwo expressions are opposite in order to ensure that the dimensions ofthe two vectors to the left and to the right of Kronecker operator arethe same in the two expressions.

Also note that in some embodiments the KP expressions can be swapped forthe two configurations:, i.e., if N₁≧N₂ we have

${W_{m_{1},m_{2},n}^{(1)} = {\frac{1}{\sqrt{Q}}\begin{bmatrix}{u_{m_{2}} \otimes v_{m_{1}}} \\{\phi_{n}{u_{m_{2}} \otimes v_{m_{1}}}}\end{bmatrix}}};$

and if N₁<N₂, we have

$W_{m_{1},m_{2},n}^{(1)} = {{\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}.}$

This applies to all the embodiments for other ranks as well.

For example, assuming antenna port numbering 2 for a 16 portconfiguration, we have:

(N₁,N₂)=(4,2) and,

$v_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; n_{1}}{O_{1}N_{1}}} & ^{j\frac{4\pi \; n_{1}}{O_{1}N_{1}}} & ^{j\frac{6\pi \; n_{1}}{O_{1}N_{1}}}\end{bmatrix}^{t}$ and ${u_{m_{2}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; n_{2}}{O_{2}N_{2}}}\end{bmatrix}^{t}};$

and

(N₁,N₂)=(2,4) and,

$v_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; n_{1}}{O_{1}N_{1}}}\end{bmatrix}^{t}$ and $u_{m_{2}} = {\begin{bmatrix}1 & ^{j\frac{2\pi \; n_{2}}{O_{2}N_{2}}} & ^{j\frac{4\pi \; n_{2}}{O_{2}N_{2}}} & ^{j\frac{6\pi \; n_{2}}{O_{2}N_{2}}}\end{bmatrix}^{t}.}$

Similarly, for 12 port configuration, we have:

(N₁,N₂)=(3,2) and,

${v_{m_{1}} = {{\begin{bmatrix}1 & ^{j\frac{2\pi \; n_{1}}{O_{1}N_{1}}} & ^{j\frac{4\pi \; n_{1}}{O_{1}N_{1}}}\end{bmatrix}^{t}\mspace{14mu} {and}\mspace{14mu} u_{m_{2}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; n_{2}}{O_{2}N_{2}}}\end{bmatrix}^{t}}};$

and

(N₁,N₂)=(2,3) and,

$v_{m_{1}} = {{\begin{bmatrix}1 & ^{j\frac{2\pi \; n_{1}}{O_{1}N_{1}}}\end{bmatrix}^{t}\mspace{14mu} {and}\mspace{14mu} u_{m_{2}}} = {\begin{bmatrix}1 & ^{j\frac{2\pi \; n_{2}}{O_{2}N_{2}}} & ^{j\frac{4\pi \; n_{2}}{O_{2}N_{2}}}\end{bmatrix}^{t}.}}$

The embodiment is applicable to the antenna port numbering 1, where(N₁,N₂)=(2,4) for config A and for (N₁,N₂)=(4,2) for config B.

Note that even though W_(m) ₁ _(,m) ₂ _(,n) ⁽¹⁾ expression is differentin two configurations, the master rank-1 codebook table such as TABLE 35can be used for both.

For rank-2, the pre-coding matrix is given by

$W_{m_{1},m_{2},m_{1}^{\prime},m_{2}^{\prime},n}^{(2)} = {\frac{1}{\sqrt{2\; Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}^{\prime}} \otimes u_{m_{2}^{\prime}}}}\end{bmatrix}}$

for N₁≧N₂ (config A), and it is

$W_{m_{1},m_{2},m_{1}^{\prime},m_{2}^{\prime},n}^{(2)} = {\frac{1}{\sqrt{2\; Q}}\begin{bmatrix}{u_{m_{2}} \otimes v_{m_{1}}} & {u_{m_{2}^{\prime}} \otimes v_{m_{1}^{\prime}}} \\{\phi_{n}{u_{m_{2}} \otimes v_{m_{1}}}} & {{- \phi_{n}}{u_{m_{2}^{\prime}} \otimes v_{m_{1}^{\prime}}}}\end{bmatrix}}$

for N₁<N₂ (config B). The expressions for rank 3-8 for the twoconfigurations can be expression similarly. Similar to rank-1, for rank2-8 also, the master rank 2-8 codebooks in this case remain the same asmentioned earlier in this disclosure.

In addition, the beam grouping schemes or (L₁,L₂) configurations orcodebook subset selection according to some embodiments of thisdisclosure are applicable straightforwardly to this case once we havethe master table for each of antenna port configurations.

In another method, if the oversampling factor in the longer and shorterdimensions of the two symmetric port configurations are the same, thenthe pre-coder for one of the symmetric port configuration is derivedfrom that for the other symmetric port configuration by applying a fixedmapping on the elements of the pre-coding vector. In one method, for theconfiguration in which N₁≧N₂ (config A), the UE derives the rank-1pre-coder as

${W_{m_{1},m_{2},n}^{(1)} = {\frac{1}{\sqrt{Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}}\end{bmatrix}}},$

and for the configuration in which N₁<N₂ (config B), the UE derives therank-1 pre-coder as

${W_{m_{1},m_{2},n}^{(1)} = {\frac{1}{\sqrt{Q}}\begin{bmatrix}{\phi \left( {v_{m_{1}} \otimes u_{m_{2}}} \right)} \\{\phi_{n}{\sigma \left( {v_{m_{1}} \otimes u_{m_{2}}} \right)}}\end{bmatrix}}},$

where the mapping function is defined as

${\sigma \begin{pmatrix}a_{0} \\a_{1} \\\vdots \\a_{N_{2} - 1} \\b_{0} \\b_{1} \\\vdots \\b_{N_{2} - 1}\end{pmatrix}} = {\begin{pmatrix}a_{0} \\b_{0} \\a_{1} \\b_{1} \\a_{2} \\\vdots \\a_{N_{2} - 1} \\b_{N_{2} - 1}\end{pmatrix}.}$

Note that here the assumption is that O₁ and O₂ in case of N₁≧N₂ is thesame as O₂ and O₁ in case of N₁<N₂, respectively. In one example, for(N₁,N₂)=(4,2) with (O₁,O₂)=(8,16),

$v_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\; \pi \; m_{1}}{32}} & ^{j\frac{4\; \pi \; m_{1}}{32}} & ^{j\frac{6\; \pi \; m_{1}}{32}}\end{bmatrix}^{t}$ and ${u_{m_{2}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{32}}\end{bmatrix}^{t}},$

hence

${{v_{m_{1}} \otimes u_{m_{2}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{32}} & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\; 2\; {\pi {(\frac{m_{1} + m_{2}}{32})}}} \\^{j\frac{4\; \pi \; m_{1}}{32}} & ^{j\; 2\; {\pi {(\frac{{2\; m_{1}} + m_{2}}{32})}}} & ^{j\frac{6\; \pi \; m_{1}}{32}} & ^{j\; 2\; {\pi {(\frac{{3m_{1}} + m_{2}}{32})}}}\end{bmatrix}};$

and for

(N₁,N₂)=(2,4) with (O₁,O₂)=(16,8),

$v_{m_{2}} = \begin{bmatrix}1 & ^{j\frac{2\; \pi \; m_{2}}{32}}\end{bmatrix}^{t}$ and ${u_{m_{1}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\; \pi \; m_{1}}{32}} & ^{j\frac{6\; \pi \; m_{1}}{32}}\end{bmatrix}^{t}},$

hence

${{v_{m_{2}} \otimes u_{m_{1}}} = \begin{bmatrix}1 & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\frac{4\pi \; m_{1}}{32}} & ^{j\; \frac{6\; \pi \; m_{1}}{32}} \\^{j\frac{2\; \pi \; m_{2}}{32}} & ^{j\; 2\; {\pi {(\frac{m_{1} + m_{2}}{32})}}} & ^{{j2\pi}{(\frac{{2\; m_{1}} + m_{2}}{32})}} & ^{j\; 2\; {\pi {(\frac{{3m_{1}} + m_{2}}{32})}}}\end{bmatrix}},$

which can be obtained by applying the permutation ρ({1 2 3 4 5 6 78})={1 3 5 7 2 4 6 8} on the components of

$\begin{bmatrix}1 & ^{j\frac{2\pi \; m_{2}}{32}} & ^{j\frac{2\pi \; m_{1}}{32}} & ^{j\; 2\; {\pi {(\frac{m_{1} + m_{2}}{32})}}} \\^{j\frac{4\; \pi \; m_{1}}{32}} & ^{j\; 2\; {\pi {(\frac{{2\; m_{1}} + m_{2}}{32})}}} & ^{j\frac{6\; \pi \; m_{1}}{32}} & ^{j\; 2\; {\pi {(\frac{{3m_{1}} + m_{2}}{32})}}}\end{bmatrix}.$

In an alternate method, the pre-coder for N₁≧N₂ can be derived byapplying a similar fixed mapping on the pre-coder for N₁<N₂ case.

For rank 2-8, the mapping can be constructed similarly.

Alternative 2: different codebooks for different antenna portconfigurations

In this alternative, we have different codebook for different antennaport configurations. In the following, we assume that the firstdimension is for the horizontal and the second dimension is for thevertical. The codebook design below, however, is applicable to the othercase in which the first dimension is for the vertical and the seconddimension is for the horizontal, or any other form of antenna portlayouts including one-dimensional. As before, we continue to assumeantenna port numbering 2 in the codebook tables. The codebook tables forantenna port numbering 1 can be constructed similarly.

In some embodiments, a UE is configured with two different rank-1 mastercodebooks for the two antenna port configurations, N₁≧N₂ (config A) andN₁<N₂ (config B). If N₁≧N₂, then the master rank-1 codebook is accordingto TABLE 35, and N₁<N₂, then the master rank-1 codebook is given byTABLE 64, that the beam grouping in the two codebooks constitute 4 beamsin the longer dimension (4 ports) and 2 beams in shorter dimension.

There are multiple alternatives for the rest of codebook parameters forthe two codebooks. In one alternative, the codebook parameters are thesame in the two codebooks, i.e., O₁, O₂, s₁, s₂, p₁, and p₂ are thesame. In another alternative, they are different. In yet anotheralternative, a subset of them is the same, and another subset isdifferent. For example, O₁ and O₂ are different, but s₁, s₂, p₁, and p₂are the same.

TABLE 64 Master codebook for 1 layer CSI reporting for (N₁, N₂) = (2, 4)and for (L₁, L₂) = (2, 4) i₂′ 0 1 2 3 Precoder W_(s) ₁ _(i) _(1,1) _(,s)₂ _(i) _(1,2) _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,1)⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,2) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(,3) ⁽¹⁾ i₂′ 4 5 6 7 Precoder W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,3)⁽¹⁾ i₂′ 8 9 10 11 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+2p) ₂ _(,0) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂_(,1) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,2) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,3) ⁽¹⁾ i₂′ 12 13 1415 Precoder W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,0) ⁽¹⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,1) ⁽¹⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,2) ⁽¹⁾ W_(s) ₁ _(i) _(1,1) _(,s)₂ _(i) _(1,2) _(+3p) ₂ _(,3) ⁽¹⁾ i₂′ 16-31 Precoder Entries 16-31constructed with replacing the second subscript _(s) ₁ _(i) _(1,1) with_(s) ₁ _(i) _(1,1) _(+p) ₁ in entries 0-15.

In some embodiments, a UE is configured with two different rank-2 mastercodebooks for the two antenna port configurations, N₁≧N₂ (config A) andN₁<N₂ (config B). If N₁≧N₂, then the master rank-2 codebook is accordingto TABLE 56 and N₁<N₂, then the master rank-2 codebook is given by TABLE65. Note that the beam grouping in the two codebooks constitute 4 beamsin the longer dimension (4 ports) and 2 beams in shorter dimension.TABLE 35 is constructed simular to TABLE 56 except that the Rel 12 8-Txrank-2 beam pairs are considered for the 4 beams in vertical dimension(2nd dimension).

Similar to rank-1 case, there are multiple alternatives for the rest ofcodebook parameters for the two codebooks. In one alternative, thecodebook parameters are the same in the two codebooks, i.e., O₁, O₂, s₁,s₂, p₁, and p₂ are the same. In another alternative, they are different.In yet another alternative, a subset of them is the same, and anothersubset is different. For example, O₁ and O₂ are different, but s₁, s₂,p₁, and p₂ are the same.

TABLE 65 Master codebook for 2 layer CSI reporting for (N_(1, N) ₂ ) =(2, 4) and for (L_(1, L) ₂ ) = (2, 4) i ₂ ′ 0 1 W_(s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,1) ⁽²⁾ i ₂ ′ 4 5

i ₂ ′ 8 9 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i ₂ ′12 13 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s)₂ _(i) _(1,2) _(+3p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,1) ⁽²⁾ i ₂ ′ 16 17W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾i ₂ ′ 20 21 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+3p) ₂_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,1) ⁽²⁾ i ₂ ′ 24 25 W_(s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(+2p) ₂ _(,1) ⁽²⁾ i ₂ ′ 28 29 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(,1) ⁽²⁾ i ₂ ′ 32 33 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i ₂ ′ 2 3

i ₂ ′ 6 7

i ₂ ′ 10 11 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s)₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2p) ₂_(,1) ⁽²⁾ i ₂ ′ 14 15 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+3p) ₂ _(,1) ⁽²⁾ i ₂ ′ 18 19 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p)₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i ₂′ 22 23 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,1) ⁽²⁾ i ₂ ′ 26 27 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(+3p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p)₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+3p) ₂ _(,1) ⁽²⁾ i ₂′ 30 31 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,1) ⁽²⁾ i ₂ ′ 34 35 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+2p) ₂ _(,1) ⁽²⁾

In some embodiments, a UE is configured with two different rank-3 andrank-4 master codebooks for the two antenna port configurations, N₁≧N₂(config A) and N₁<N₂ (config B). If N₁≧N₂, then the master rank-3 andrank-4 codebooks are according to TABLE 40 and TABLE 41, respectively,and if N₁<N₂, then they are given TABLE 8 and TABLE 67, respectively,wherein the corresponding rank 3 precoder is either

$W_{m_{1},m_{2},m_{2}^{\prime},m_{2}^{''}}^{(3)} = {\frac{1}{\sqrt{3Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1}} \otimes u_{m_{2}^{''}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}^{\prime}}} & {{- v_{m_{1}}} \otimes u_{m_{2}^{''}}}\end{bmatrix}}$ or${{\overset{\sim}{W}}_{m_{1},m_{2},m_{2}^{\prime},m_{2}^{''}}^{(3)} = {\frac{1}{\sqrt{3Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1}} \otimes u_{m_{2}^{''}}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}^{\prime}}} & {{- v_{m_{1}}} \otimes u_{m_{2}^{''}}}\end{bmatrix}}},$

and the corresponding rank 4 precoder is

$W_{m_{1},m_{2},m_{2}^{\prime},n}^{(4)} = {{\frac{1}{\sqrt{4Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}^{\prime}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}^{\prime}}} \\{\phi_{n}{v_{m_{1}} \otimes u_{m_{2}}}} & {\phi_{n}{v_{m_{1}} \otimes u_{m_{2}^{\prime}}}} & {{- \phi_{n}}{v_{m_{1}} \otimes u_{m_{2}}}} & {{- \phi_{n}}{v_{m_{1}} \otimes u_{m_{2}^{\prime}}}}\end{bmatrix}}.}$

Note that the beam grouping in the two codebooks constitute 4 beams inthe longer dimension (4 ports) and 2 beams in shorter dimension. TABLE66 and TABLE 67 respectively are constructed simular to TABLE 40 andTABLE 41 except that the four orthogonal beam pairs{(0,8),(2,10),(4,12),(6,14)} are considered in the vertical dimension(2nd dimension).

In the longer dimension (4 ports), the codebook parameters are legacyRel12 8-Tx parameters, i.e., if N₁≧N₂, then s₁=8, p₁=1, and i_(1,1)=0-3,and if N₁<N₂, then s₂=8, p₂=1, and i_(1,2)=0-3. There are multiplealternatives for the parameters in the other dimension of the twocodebooks. In one alternative, they are the same in both codebooks,i.e., O₂, s₂, and p₂ in case of N₁≧N₂ are the same as O₁, s₁, and p₁ incase of N₁<N₂. In another alternative, they are different. In yetanother alternative, a subset of them is the same, and another subset isdifferent. For example, O₁ in case of N₁≧N₂ and O₂ in case of N₁<N₂ aredifferent, but other parameters are the same.

TABLE 66 Master codebook for 3 layer CSI reporting for (N₁, N₂) = (2, 4)and for (L₁, L₂) = (2, 4) i₂′ 0 1 2 3 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,s) ₂ _(i) _(1,2) _(,s) ₂ _(i) _(1,2) ₊₈ ⁽³⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+8,s) ₂ _(i) _(1,2) _(,s) ₂ _(i) _(1,2) ₊₈⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+8,s) ₂_(i) _(1,2) _(,s) ₂ _(i) _(1,2) ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+8,s) ₂ _(i) _(1,2) _(+8,s) ₂ _(i) _(1,2) ⁽³⁾ i₂′4 5 6 7 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+2,s) ₂ _(i) _(1,2)_(+2,s) ₂ _(i) _(1,2) ₊₁₀ ⁽³⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+10,s) ₂ _(i) _(1,2) _(+2,s) ₂ _(i) _(1,2) ₊₁₀ ⁽³⁾ {tilde over(W)}_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+10,s) ₂ _(i) _(1,2)_(+2,s) ₂ _(i) _(1,2) ₊₂ ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+10,s) ₂ _(i) _(1,2) _(+10,s) ₂ _(i) _(1,2) ₊₂ ⁽³⁾ i₂′ 8 910 11 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+4,s) ₂ _(i) _(1,2)_(+4,s) ₂ _(i) _(1,2) ₊₁₂ ⁽³⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+12,s) ₂ _(i) _(1,2) _(+4,s) ₂ _(i) _(1,2) ₊₁₂ ⁽³⁾ {tilde over(W)}_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+12,s) ₂ _(i) _(1,2)_(+4,s) ₂ _(i) _(1,2) ₊₄ ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+12,s) ₂ _(i) _(1,2) _(+12,s) ₂ _(i) _(1,2) ₊₄ ⁽³⁾ i₂′ 1213 14 15 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+6,s) ₂ _(i) _(1,2)_(+6,s) ₂ _(i) _(1,2) ₊₁₄ ⁽³⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+14,s) ₂ _(i) _(1,2) _(+6,s) ₂ _(i) _(1,2) ₊₁₄ ⁽³⁾ {tilde over(W)}_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+14,s) ₂ _(i) _(1,2)_(+6,s) ₂ _(i) _(1,2) ₊₆ ⁽³⁾ {tilde over (W)}_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+14,s) ₂ _(i) _(1,2) _(+14,s) ₂ _(i) _(1,2) ₊₆ ⁽³⁾ i₂′16-31 Entries 16-31 constructed with replacing the second subscript _(s)₁ _(i) _(1,1) with _(s) ₁ _(i) _(1,1) _(+p) ₁ in entries 0-15.

TABLE 67 Master codebook for 4 layer CSI reporting for (N₁, N₂) = (2, 4)and for (L₁, L₂) = (2, 4) i₂′ 0 1 2 3 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,s) ₂ _(i) _(1,2) _(+8,0) ⁽⁴⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,s) ₂ _(i) _(1,2) _(+8,1) ⁽⁴⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+2,s) ₂ _(i) _(1,2) _(+10,0) ⁽⁴⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+2,s) ₂ _(i) _(1,2) _(+10,1) ⁽⁴⁾ i₂′ 4 5 6 7 W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+4,s) ₂ _(i) _(1,2) _(+12,0) ⁽⁴⁾ W_(s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+4,s) ₂ _(i) _(1,2) _(+12,1) ⁽⁴⁾ W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+6,s) ₂ _(i) _(1,2) _(+14,0) ⁽⁴⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+6,s) ₂ _(i) _(1,2) _(+14,1)⁽⁴⁾ i₂′ 8-15 Entries 8-15 constructed with replacing the secondsubscript _(s) ₁ _(i) _(1,1) with _(s) ₁ _(i) _(1,1) _(+p) ₁ in entries0-7.

Rank 3-4 codebooks corresponding to the case in which we have differentbeams (0,1) and (1,0) in the shorter dimension (2 ports), according toTABLE 45 and TABLE 52 can be constructed similarly.

In some embodiments, a UE is configured with two different rank 5-8master codebooks for the two antenna port configurations, N₁≧N₂ (configA) and N₁<N₂ (config B). If N₁≧N₂, then the master rank 5-8 codebooksare according to TABLE 43, and if N₁<N₂, then they are given by TABLE68, wherein the corresponding rank-5 precoder is

${W_{m_{1},m_{2}}^{(5)} = {\frac{1}{\sqrt{5Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}}\end{bmatrix}}},$

the corresponding rank-6 precoder is

${W_{m_{1},m_{2}}^{(6)} = {\frac{1}{\sqrt{6Q}}\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 16}}\end{bmatrix}}},$

the corresponding rank-7 precoder is

$W_{m_{1},m_{2}}^{(7)} = {\frac{1}{\sqrt{7Q}}{\quad{\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {v_{m_{1}} \otimes u_{m_{2} + 24}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 16}} & {v_{m_{1}} \otimes u_{m_{2} + 24}}\end{bmatrix},}}}$

and the corresponding rank-8 precoder is

$W_{m_{1},m_{2}}^{(8)} = {\frac{1}{\sqrt{8Q}}{\quad{\begin{bmatrix}{v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {v_{m_{1}} \otimes u_{m_{2} + 24}} & {v_{m_{1}} \otimes u_{m_{2} + 24}} \\{v_{m_{1}} \otimes u_{m_{2}}} & {{- v_{m_{1}}} \otimes u_{m_{2}}} & {v_{m_{1}} \otimes u_{m_{2} + 8}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 8}} & {v_{m_{1}} \otimes u_{m_{2} + 16}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 16}} & {v_{m_{1}} \otimes u_{m_{2} + 24}} & {{- v_{m_{1}}} \otimes u_{m_{2} + 24}}\end{bmatrix}.}}}$

Note that the beam grouping in the two codebooks constitute 4 orthogonalbeams {0,8,16,24} in the longer dimension (4 ports) and 2 beams inshorter dimension. TABLE 68 is constructed simular to TABLE 43 exceptthat the four orthogonal beams {0,8,16,24} are considered in thevertical dimension (2nd dimension).

In the longer dimension (4 ports), the codebook parameters are legacyRel12 8-Tx parameters, i.e., if N₁≧N₂, then s₁=2, p₁=1, and i_(1,1)=0-3for rank 5-7 and i_(1,1)=0 for rank 8, and if N₁<N₂, then s₂=2, p₂=1,and i_(1,2)=0-3 for rank 5-7 and i_(1,2)=0 for rank 8. There aremultiple alternatives for the parameters in the other dimension of thetwo codebooks. In one alternative, they are the same in both codebooks,i.e., O₂, s₂, and p₂ in case of N₁≧N₂ are the same as O₁, s₁, and p₁ incase of N₁<N₂. In another alternative, they are different. In yetanother alternative, a subset of them is the same, and another subset isdifferent. For example, O₁ in case of N₁≧N₂ and O₂ in case of N₁<N₂ aredifferent, but other parameters are the same.

TABLE 68 Master codebook for r = {5, 6, 7, 8} layer CSI reporting for(N₁, N₂) = (2, 4) and for (L₁, L₂) = (2, 4) i_(2′) 0 1 Precoder W_(s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) ^((r)) W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) ^((r))

Rank 5-8 codebooks corresponding to the case in which we have differentbeams (0,1) and (1,0) in the shorter dimension (2 ports), according toTABLE 45 and TABLE 52 can be constructed similarly.

In some embodiment, the configuration about the selected beam group orcodebook subset selection from the master codebook of rank 1-8 in thisdifferent master codebook case is according to some embodiments of thisdisclosure, wherein the configuration of the beam group is dependentupon the configured (N₁, N₂). For example, for N₁≧N₂, the beam groupsare as shown in FIG. 47 and for N₁<N₂, they are the transpose of thecorresponding beam groups in FIG. 47.

Concrete Example

FD-MIMO codebook of rank 1-8 is configured with N₁,N₂,O₁,O₂ via RRCsignaling, where the configured values of N₁ and N₂ are from the set{1,2,3,4,6,8 } such that 2N₁·N₂={8, 12, 16}, and the configured valuesof O₁ and O₂ are from the set {2,4,8}. The codebook has a doublecodebook structure: W=W₁W₂, according to some embodiments of thisdisclosure. In particular, W₁=

$\begin{pmatrix}{X_{1}^{m_{1}} \otimes X_{2}^{m_{2}}} & 0 \\0 & {X_{1}^{m_{1}} \otimes X_{2}^{m_{2}}}\end{pmatrix},$

where

-   -   m_(i) is the index for X_(i);    -   X₁ is a N₁×L₁ matrix with L₁ column vectors being an O₁x        oversampled DFT vector of length N₁:

${v_{l} = \begin{bmatrix}1 & ^{\frac{j\; 2\; \pi \; l}{N_{1}O_{1}}} & \ldots & ^{\frac{j\; 2\; {\pi {({N_{1} - 1})}}l}{N_{1}O_{1}}}\end{bmatrix}^{t}};$

and

-   -   X₂ is a N₂×L₂ matrix with L₂ column vectors being an O₂x        oversampled DFT vector of length N₂:

$v_{l} = {\begin{bmatrix}1 & ^{\frac{j\; 2\; \pi \; l}{N_{2}O_{2}}} & \ldots & ^{\frac{j\; 2\; {\pi {({N_{2} - 1})}}l}{N_{2}O_{2}}}\end{bmatrix}^{t}.}$

For rank 1-4 W₂, the codebook table has 4×2 beams, i.e., (L₁, L₂)=(4,2)where a 1st dimension is the longer dimension and a 2nd dimension is theshorter dimension of the configured antenna port layout or (N₁,N₂). Asubset of codewords from the codebook table is selected for W₂ or i₂ tobe reported.

The number of i₂ hypotheses after CSS will be 16 for rank 1, 2 and 3,which is smaller than the total number of i₂ indices in therank-specific codebook table. The CSS allows non-adjacent 2D beamsampling.

The choice of subset is configured via RRC in the form on CSSconfiguration, which determines a 2D beam group used in W₁. For each(N₁, N₂) pair, the indicated 2D beam group satisfies the conditionL₁·L₂≦4. For example, the indicated beam group is one of the followingfour:

BG0: a beam group related to either (L₁,L₂)=(4,1) or (1,4), wherein the4 beams are along the longer dimension. An example of such a beam groupis 820 in FIG. 35;

BG1: a beam group corresponding to (L₁,L₂)=(2,2), which corresponds to asquare. A few examples of such a beam group are 830 a, 830 b, 830 c inFIG. 35;

BG2: a beam group corresponding to (L₁,L₂)=(2,2), which corresponds tonon-adjacent 2D beams or checkerboard. A few examples of such a beamgroup are 830 d, 380 e, 830 f in FIG. 35; and

BG3: a beam group corresponding to (L₁,L₂)=(1,1), which corresponds toone beam selection. An example of such a beam group is 860 in FIG. 35.

Note that the W₂ payload size varies according to 2D beam groupconfiguration. For example, BG0-BG2, the payload is 4 bits for rank-1 i₂reporting, and it is 2 bits for BG3 assuming QPSK alphabet {1,j,−1,−j}for co-phase reporting, and no beam selection information is necessaryhere.

Furthermore, the beam groups (BG) can be classified into two sets:

-   -   Set 1: This set corresponds to beam groups with (L₁, L₂) such        that either L₁ or L₂>1. An example of beam groups in this set is        BG0, BG1, and BG2, which satisfy L₁·L₂=4.        -   i₂ payload: The legacy Rel12 W₂ (or i₂) payload size can be            used, i.e., 4 bits for rank 1-3 i₂ reporting and 3 bits for            rank-4 i₂ reporting.        -   i_(i) (i_(1,1), i_(1,2)) payload: For W₁ or i₁ reporting,            ceil(log₂(N₁O₁/2))+ceil(log₂(N₂O₂/2)) bits are used where            the beam skipping (or beam group spacing) parameters are            s₁=s₂=2.    -   Set 2: This set corresponds to L₁·L₂=1 (or L₁=L₂=1, one beam),        and hence no beam selection is needed. An example of this set is        BG3.        -   i₂ payload: 2 bits are used for rank 1-4 i₂ reporting.        -   i₁ (i_(1,1), i_(1,2)) payload: For W₁ or i₁ reporting,            ceil(log₂(N₁O₁))+ceil(log₂(N₂O₂)) bits are used where the            beam skipping (or beam group spacing) parameters are            s₁=s₂=1.

In some embodiments, a UE can be configured with either Set 1 or Set 2by RRC. In one example, only one BG is included in Set 1. In anotherexample, the UE is also configured with a BG if Set 1 is configured.Then, the UE will report PMI, of which the payload size is determineddependent upon which set is configured; in addition the UE will use theconfigured BG to select a beam and corresponding precoder.

In some embodiments, a UE can be configured with a BG out of BG0, BG1,BG2, and BG3 by RRC. The UE determines the set to which the configuredBG belongs, which in turn determines the payload size for PMI reporting.The UE then uses the configured BG to select a beam and correspondingprecoder.

In some embodiments, a UE is configured to select and report one of Set1 and Set 2 to eNB, which uses the selected set to configure PMIcodebook. In one example, only one BG is included in Set 1. In anotherexample, UE also selects a BG if it reports Set 1.

In some embodiments, a UE is configured to select and report one of BG0,BG1, BG2, and BG3 to eNB, which uses the selected BG to configure PMIcodebook.

More Rank-2 Codebook Designs: Design 1

FIG. 50 illustrates the master rank-2 codebook 5000 designed accordingto Design 1 according to the present disclosure. The embodiment shown inFIG. 50 is for illustration only. Other embodiments could be usedwithout departing from the scope of the present disclosure.

The codebook comprises of rank-2 beam pairs corresponding to four rank-2configurations (or beam grouping schemes):

Config 1 is for (L₁,L₂)=(1,1) configuration and the selected rank-2 beampair is located at{(00,00)};

Config 2 is for (L₁,L₂)=(2,2)—square configuration, which corresponds to4 Type 1 pairs {(00,00), (00,11), (11,00), (11,11)}, 2 Type 2-1 pairs{(01,00), (01,11)}, and 2 Type 2-3 pairs {(01,01), (01,10)};

Config 3 is for (L₁,L₂)=(2,2)—checker board configuration, whichcorresponds to 4 Type 1 pairs {(00,00), (00,22), (11,11), (11,33)}, 3Type 2-1 pairs {(03,00), (12,11), (13,11)}, and 1 Type 2-3 pairs{(01,01)}; and

Config 4 is for (L₁,L₂)=(4,1) configuration and the selected rank-2 beampairs correspond to 8 pairs located at{(x,00)} where x is according toTABLE 37.

In total, the codebook comprises of 16 rank-2 beam pair combinations,which are shown as a shaded and pattern squares in the 2D grid (x,y),where the first component x corresponds to the legacy Rel12 8-Tx basedrank-2 beam pairs for the first dimension (L₁=4, see TABLE 37) and thesecond component y corresponds to the beam pairs for the seconddimension (L₂=2) according to TABLE 52. The shaded and pattern squaresrepresent the rank-2 i₂ (or i_(2,1) and i_(2,2)) indices that areselected based at least one of the four configurations (or beam groupingschemes) and the white squares represent the indices that are notselected by any configurations.

TABLE 69 shows the rank-2 (2 layer) master codebook according to thisdesign that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein TABLE 37 and TABLE 52, respectively are used forthe beam pairs in the longer and the shorter dimension to construct themaster rank-2 codebook. Note that the number of rank-2 i₂ indices inthis master codebook is 32.

TABLE 69 Master codebook for 2 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0-15 Entries 0-15 are identical to those in TABLE 38. i₂′ 16 17W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾i₂′ 20 21 W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁_(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 24 25 W_(s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+2p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,1) ⁽²⁾ i₂′ 28 29 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 0-15 Entries 0-15 are identical tothose in TABLE 38. i₂′ 18 19 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 22 23W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s)₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,1) ⁽²⁾ i₂′ 26 27 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 30 31W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾

More Rank-2 Codebook Designs: Design 2

FIG. 51 illustrates the master rank-2 codebook 5100 designed accordingto Design 2 according to embodiments of the present disclosure. Theembodiment shown in FIG. 51 is for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

The codebook comprises of rank-2 beam pairs corresponding to four rank-2configurations (or beam grouping schemes):

-   -   Config 1 is for (L₁,L₂)=(1,1) configuration and the selected        rank-2 beam pair is located at{(00,00)};    -   Config 2 is for (L₁,L₂)=(2,2)—square configuration, and has two        option:        -   Option 0 corresponds to 4 Type 1 pairs {(00,00), (00,11),            (11,00), (11,11)}, 2 Type 2-1 pairs {(01,00), (01,11)}, and            2 Type 2-3 pairs {(01,01), (01,10)}, and        -   Option 1 corresponds to 4 Type 1 pairs {(00,00), (00,11),            (11,00), (11,11)}, 2 Type 2-1 pairs {(01,00), (01,11)}, and            2 Type 2-2 pairs {(00,01), (11,10)};    -   Config 3 is for (L₁,L₂)=(2,2)—checker board configuration, which        corresponds to 4 Type 1 pairs {(00,00), (00,22), (11,11),        (11,33)}, 2 Type 2-1 pairs {(01,00), (03,00)}, and 2 Type 2-3        pairs {(12,01), (13,01)}; and    -   Config 4 is for (L₁,L₂)=(4,1) configuration and the selected        rank-2 beam pairs correspond to 8 pairs located at{(x,00)} where        x is according to TABLE 37.

In total, the codebook comprises of 16 rank-2 beam pair combinations foreach of Option 0 and Option 1, which are shown as a shaded and patternsquares in the 2D grid (x,y), where the first component x corresponds tothe legacy Rel12 8-Tx based rank-2 beam pairs for the first dimension(L₁=4, see TABLE 37) and the second component y corresponds to the beampairs for the second dimension (L₂=2) according to TABLE 52. The shadedand pattern squares represent the rank-2 i₂ (or i_(2,1) and i_(2,2))indices that are selected based at least one of the four configurations(or beam grouping schemes) and the white squares represent the indicesthat are not selected by any configurations.

TABLE 70 shows the rank-2 (2 layer) master codebook according to thisdesign that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein TABLE 37 and TABLE 52, respectively are used forthe beam pairs in the longer and the shorter dimension to construct themaster rank-2 codebook. Note that the number of rank-2 i₂ indices inthis master codebook is 32.

TABLE 70 Master codebook for 2 layer CSI reporting for (L₁, L₂) = (4, 2)i₂′ 0-15 Entries 0-15 are identical to those in TABLE 38. i₂′ 16 17W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾i₂′ 20 21 W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁_(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 24 25 W_(s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1)⁽²⁾ i₂′ 28 29 Option 0: Option 0: W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i)_(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ Option 1: Option 1: W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p)₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 0-15 Entries 0-15 areidentical to those in TABLE 38. i₂′ 18 19 W_(s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1)⁽²⁾ i₂′ 22 23 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁_(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 26 27 W_(s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s)₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i₂′ 30 31Option 0: Option 0: W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(,1) ⁽²⁾ Option 1: Option 1: W_(s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i)_(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾

FIG. 52 illustrates beam grouping options 5200 for Config 1, Config 2,Config 3, and Config 4. The embodiment shown in FIG. 51 is forillustration only. Other embodiments could be used without departingfrom the scope of the present disclosure.

In some embodiments, a UE is configured with one of Option 0 and Option1 if it is configured with Config 2.

In some embodiments, a UE is configured with Config 2 with thepre-determined option, for example Option 0.

In some embodiments, a UE is configured with one of Config 1, Config 2,Config 3, and Config 4. Depending on the configuration, the UE selectsi′₂ indices in TABLE 69 (or TABLE 70) according to TABLE 71 andsequentially maps them to 0-1 for Config 1, and 0 0-15 for Config 2-4 inorder to report i₂ PMI.

In one method, a UE uses the beam group spacing parameters (s₁,s₂)according to TABLE 71 depending on the configuration.

In one method, a UE uses the following values in TABLE 69 (or TABLE 70):i_(1,1)=0,1, . . . , O₁N₁/s₁−1; i_(1,2)=0,1, . . . , O₂N₂/s₂−1; and p₁=1and p₂=1.

TABLE 71 Selected i₂′ indices according to configurations (TABLE 69 andTABLE 70) Config Selected i₂′ indices (s₁, s₂) 1 0-1 (1, 1) 2 0-3, 8-9,16-19, 22-23, 28-31 (2, 2) 3 0-1, 4-5, 12-13, 18-21, 24-27, 28-29 (2, 2)4 0-15 (2, 2)

In some embodiments, a UE reports a preferred configuration, selectedfrom Config 1, Config 2, Config 3, and Config 4.

In some embodiments, the master rank-2 codebook is designed by selectingat least one rank-2 beam pair option from multiple options shown in FIG.52 for each of Config 1, Config 2, Config 3, and Config 4.

In one method, from the designed master codebook, a UE is configuredwith one configuration from the Config 1, Config 2, Config 3, and Config4 that comprise the master codebook according to some embodiments ofthis disclosure.

In another method, from the designed master codebook, a UE reports oneconfiguration from the Config 1, Config 2, Config 3, and Config 4 thatcomprise the master codebook according to some embodiment.

Rank 2 Codebook Design Based on Nested Property with Rank 1 Codebook

FIG. 53 illustrates rank 2 beam pairs 5300 based on nested property withrank 1 beams according to embodiments of the present disclosure. Theembodiment shown in FIG. 51 is for illustration only. Other embodimentscould be used without departing from the scope of the presentdisclosure.

In some embodiments, the master rank-2 codebook is designed with thenested property with the rank-1 codebook in the sense that the rank-2beam pairs for the two layers are formed using the beams in the rank-1codebook (TABLE 35).

In some embodiments, the nested master rank-2 codebook is designed asshown in FIG. 53. The codebook comprises of rank-2 beam pairscorresponding to four configurations (or beam grouping schemes), namelyConfig 1, Config 2, Config 3, and Config 4, where:

Config 1 is for (L₁,L₂)=(1,1) configuration;

Config 2 is for (L₁,L₂)=(2,2)—square configuration;

Config 3 is for (L₁,L₂)=(2,2)—checker board configuration; and

Config 4 is for (L₁,L₂)=(4,1) configuration.

Note that Config 1 corresponds to a single beam located at (0,0), andhence the corresponding rank-2 beam pair is (00,00).

Config 2-4 correspond to beam grouping schemes with 4 beams. As shown inthe leftmost column of FIG. 53, for each of Config 2, Config 3, andConfig 4, the four rank-1 beams are numbered as 0, 1, 2, and 3. Fromthese numbered rank-1 beams, eight rank-2 beam pairs are constructed asfollows:

-   -   Config 2 has three options to construct nested rank-2 beam        pairs:        -   Option 0: In this option, the four beams (0,0), (0,1),            (1,1), and (1,0) are first numbered as 0,1,2, and 3            respectively, and then legacy 8-Tx rank-2 beam pairs are            formed according to TALBE 35;        -   Option 1: In this option, the legacy 2-Tx rank-2 beam pairs            (0,0), (1,1), and (0,1) are considered in one dimension            d={1,2}, and the same beam pair (0,0) and (1,1) are            considered in the other dimension; and        -   Option 2: In this option, 2 diagonal beam pairs            corresponding to {(0,0),(1,1)} and {(0,1),(1,0)}, and 2            horizontal (or first or longer dimension) beam pairs            corresponding to {(0,0),(0,1)} and {(1,0),(1,1)} beam pairs            are considered; and    -   Config 3 and 4 rank-2 beam pairs are according to the legacy        Rel10 rank-2 beam pairs (TABLE 35).

In the middle column of FIG. 53, the corresponding eight rank-2 beampairs are shown as grey and three different pattern squares, and theyare also numbered as 0-7. Note that for Config 2, three different rank-2beam pairs are shown corresponding to Options 0-2. TABLE 72 tabulatesthe rank-1 beams and rank-2 beam pairs according to this constructionfor the four configurations.

The rightmost column of FIG. 53 shows all rank-2 beam pairs according tothis construction. Note that there are 18 (17) rank-2 beam pairs forOptions 0-1 (Option 2) that are numbered as 0-17 (16) in the figure. Theshaded and pattern squares represent the rank-2 beam pairs that areselected based at least one of the four configurations (or beam groupingschemes) and the white squares represent the indices that are notselected by any configurations.

TABLE 72 1: Rank 2 beam pairs with nested property with rank 1 beamsRank 1 beams Rank 2 beam pairs (1st dim, 2nd dim) (1st dim pair, 2nd dimpair) Configurations 0 1 2 3 0 1 2 3 4 5 6 7 Config 1 (0,0) — — — (00,00) — — — — — — — Config 2 (0,0) (0,1) (1,1) (1,0) (00, 00) (00, 11)(11, 11) (11, 00) (01, 00) (01, 11) (01, 00) (01, 10) (Option 0) Config2 (01, 00) (01, 11) (Option 1) Config 2 (01, 01) (01, 10) (Option 0)Config 3 (0,0) (1,1) (2,0) (3,1) (00, 00) (11, 11) (22, 00) (33, 11)(01, 01) (12, 10) (03, 01) (13, 11) Config 4 (0,0) (1,0) (2,0) (3,0)(00, 00) (11, 00) (22, 00) (33, 00) (01, 00) (12, 00) (03, 00) (13, 00)

TABLE 73 shows the nested rank-2 (2 layer) master codebook according tothis design that can be used for any of Q=12, 16 and 32 antennaconfigurations, wherein TABLE 72 is used for the nested rank-2 beampairs. Note that the number of rank-2 i′₂ indices in this mastercodebook is 36 for Options 0-1 and is 34 for Option 2.

TABLE 73 Nested master codebook for 2 layer CSI reporting for (L₁, L₂) =(4, 2) i_(2′) 0-15 Entries 0-15 are identical to those in TABLE 38.i_(2′) 16 17 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁_(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,1) ⁽²⁾ i_(2′) 20 21 W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i)_(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s)₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i_(2′) 2425 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i)_(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+3p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i_(2′) 28 29 W_(s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂_(i) _(1,2) _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+2p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾i_(2′) 32 33 Option 0 and 2: Option 0 and 2: W_(s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,1) ⁽²⁾ Option 1: Option 1: W_(s) ₁_(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁_(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s)₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,1) ⁽²⁾ i_(2′) 0-15 Entries 0-15 are identical to those in TABLE 38.i_(2′) 18 19 W_(s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂_(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1)_(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i_(2′) 22 23 W_(s) ₁ _(i)_(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1)⁽²⁾ i_(2′) 26 27 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i)_(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1)_(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+p) ₁ _(,s) ₂ _(i) _(1,2)_(+p) ₂ _(,1) ⁽²⁾ i_(2′) 30 31 W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s)₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(+3p) ₁ _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾ i_(2′) 34 35 Option 0 and 1: Option 0 and1: W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(,s) ₁ _(i) _(1,1) _(,s) ₂_(i) _(1,2) _(+p) ₂ _(,0) ⁽²⁾ W_(s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2)_(,s) ₁ _(i) _(1,1) _(,s) ₂ _(i) _(1,2) _(+p) ₂ _(,1) ⁽²⁾

In some embodiments, a UE is configured with one of Config 1, Config 2,Config 3, and Config 4. Depending on the configuration, the UE selectsi′₂ indices in TABLE 73 according to TABLE 74 and sequentially maps themto 0-1 for Config 1, and 0 0-15 for Config 2-4 in order to report i₂PMI.

In one method, a UE uses the beam group spacing parameters (s₁,s₂)according to TABLE 74 depending on the configuration.

In one method, a UE uses the following values in TABLE 73: i_(1,1)=0,1,. . . , O₁N₁/s₁−1; i_(1,2)=0,1, . . . , O₂N₂/s₂−1; and p₁=1 and p₂=1.

TABLE 74 Selected i₂′ indices according to configurations (TABLE 73)Config Selected i₂′ indices (s₁, s₂) 1 0-1 (1, 1) 2 (Option 0) 0-3, 8-9,16-19, 22-23, 32-35 (2, 2) 2 (Option 1) 0-3, 8-9, 16-19, 22-23, 32-35(2, 2) 2 (Option 2) 0-3, 8-9, 16-19, 22-23, 26-27, 32-33 (2, 2) 3 0-1,4-5, 18-21, 24-31 (2, 2) 4 0-15 (2, 2)

In some embodiments, the nested master rank-2 beam pairs are obtained byselecting eight out of ten rank-2 beam pairs shown in TABLE 75. Notethat beam pair indices 0-7 correspond to legacy Rel10 rank-2 beam pairs,and beam pair indices 8-9 correspond to non-Rel10 rank-2 beam pairs.

TABLE 75 List of all rank-2 beam pairs from four beams Beam pair index 01 2 3 4 5 6 7 8 9 (first layer, second layer) (0, 0) (1, 1) (2, 2) (3,3) (0, 1) (1, 2) (0, 3) (1, 3) (0, 2) (2, 3)

The corresponding nested master rank-2 codebook can be constructedsimilar to the previous and other embodiments of this disclosure.

To aid the Patent Office and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims or claimelements to invoke 35 U.S.C. §112(f) unless the words “means for” or“step for” are explicitly used in the particular claim. Use of any otherterm, including without limitation “mechanism,” “module,” “device,”“unit,” “component,” “element,” “member,” “apparatus,” “machine,”“system,” “processor,” or “controller,” within a claim is understood bythe applicants to refer to structures known to those skilled in therelevant art and is not intended to invoke 35 U.S.C. §112(f).

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed:
 1. A user equipment (UE) capable of communicating witha base station, the UE comprising: a transceiver configured to: receivedownlink signals indicating precoder codebook parameters, the downlinksignal including: first and second quantities of antenna portsindicating respective quantities of antenna ports in first and seconddimensions; first and second oversampling factors indicating respectiveoversampling factors for DFT beams in the first and second dimensions;either at least one beam group configuration among a plurality of beamgroup configurations or first and second quantities of beams indicatingrespective quantities of beams in the first and second dimensionsforming a beam group; and first and second beam skip numbers indicatingrespective differences of leading beam indices of two adjacent beamgroups in the first and second dimensions; and a controller configuredto: determine a precoder, using the received precoder codebookconfiguration; determine a plurality of precoding matrix indicators(PMIs) based on the received downlink signals; and cause the transceiverto transmit uplink signals containing the plurality of PMIs to the basestation.
 2. The UE of claim 1, wherein the transceiver is furtherconfigured to: receive first and second beam spacing numbers indicatinga respective difference of two adjacent beam indices within each beamgroup in the first and second dimensions.
 3. The UE of claim 1, whereinthe transceiver is further configured to: receive first and secondcodebook restriction parameters indicating a restriction on at least oneof beam skipping performed based on the first and second beam skipnumbers, beam spacing performed based on the first and second beamspacing numbers, and beam grouping performed based on at least one beamgroup configuration in the first and second dimensions, wherein eachcodebook restriction parameter is in a bitmap format.
 4. The UE of claim1, wherein the transceiver is further configured to: receive first andsecond quantities of subset beams indicating respective quantitites ofsubset beams in the first and second dimensions within each beam groupof the configured codebook.
 5. The UE of claim 1, wherein thetransceiver is further configured to: receive a configuration numberindicating one of a plurality of beam grouping schemes, each beamgrouping scheme comprising a pattern of selected beams within each beamgroup of the configured codebook, wherein each beam grouping scheme hasa different pattern of selected beams for different first and secondquantities of subset beams.
 6. The UE of claim 5, wherein the selectedbeams within each beam group are orthogonal to one another in at leastone of first and second dimensions.
 7. The UE of claim 1, wherein the UEis configured with the first and second dimension codebook parameters,and codebook restriction parameters via a higher-layer signaling.
 8. Abase station capable of communicating with a user equipment (UE), thebase station comprising: a transmitter configured to: transmit downlinksignals indicating precoder codebook parameters, the downlink signalincluding: first and second quantitites of antenna ports indicatingrespective quantitites of antenna ports in the first and seconddimensions; first and second oversampling factors indicating respectiveoversampling factors for DFT beams in the first and second dimensions;either at least one beam group configuration among a plurality of beamgroup configurations or first and second quantitites of beams indicatingrespective quantitites of beams in the first and second dimensionsforming a beam group; and first and second beam skip numbers indicatingrespective differences of leading beam indices of two adjacent beamgroups in the first and second dimensions; and a receiver configured to:receive uplink signals containing a plurality of precoding matrixindicators (PMIs) from the UE; and determine a precoder, using thereceived PMIs.
 9. The base station of claim 8, wherein the transceiveris further configured to: transmit first and second beam spacing numbersindicating a respective difference of two adjacent beam indices withineach beam group in the first and second dimensions.
 10. The base stationof claim 8, wherein the transceiver is further configured to: transmitfirst and second codebook restriction parameters indicating arestriction on at least one of beam skipping performed based on thefirst and second beam skip numbers, beam spacing performed based on thefirst and second beam spacing numbers, and beam grouping performed basedon at least one beam group configuration in the first and seconddimensions, wherein each codebook restriction parameter is in a bitmapformat.
 11. The base station of claim 8, wherein the transceiver isfurther configured to: transmit first and second quantities of subsetbeams indicating respective quantities of subset beams in the first andsecond dimensions within each beam group of the configured codebook. 12.The base station of claim 8, wherein the transceiver is furtherconfigured to: transmit a configuration number indicating one of aplurality of beam grouping schemes, each beam grouping scheme comprisinga pattern of selected beams within each beam group of the configuredcodebook, wherein each beam grouping scheme has a different pattern ofselected beams for different first and second quantities of subsetbeams.
 13. The base station of claim 12, wherein the selected beamswithin each beam group are orthogonal to one another in at least one offirst and second dimensions.
 14. The base station of claim 8, whereinthe base station transmits the first and second dimension codebookparameters and codebook restriction parameters via a higher-layersignaling.
 15. A method of operating a base station capable ofcommunicating with a user equipment (UE), the method comprising:transmitting downlink signals indicating precoder codebook parameters,the downlink signal including: first and second quantitites of antennaports indicating respective quantities of antenna ports in the first andsecond dimensions; first and second oversampling factors indicatingrespective oversampling factors for DFT beams in the first and seconddimensions; either at least one beam group configuration among aplurality of beam group configurations or first and second quantities ofbeams indicating respective quantities of beams in the first and seconddimensions forming a beam group; and first and second beam skip numbersindicating respective differences of leading beam indices of twoadjacent beam groups in the first and second dimensions; receivinguplink signals containing a plurality of precoding matrix indicators(PMIs) from the UE; and determining a precoder, using the received PMIs.16. The method of claim 15, the method further comprising: transmittingfirst and second beam spacing numbers indicating a respective differenceof two adjacent beam indices within each beam group in the first andsecond dimensions.
 17. The method of claim 15, the method furthercomprising: transmitting first and second codebook restrictionparameters indicating a restriction on at least one of beam skippingperformed based on the first and second beam skip numbers, beam spacingperformed based on the first and second beam spacing numbers, and beamgrouping performed based on at least one beam group configuration in thefirst and second dimensions, wherein each codebook restriction parameteris in a bitmap format.
 18. The method of claim 15, the method furthercomprising: transmitting first and second quantities of subset beamsindicating respective quantities of subset beams in the first and seconddimensions within each beam group of the configured codebook.
 19. Themethod of claim 15, the method further comprising: transmitting aconfiguration number indicating one of a plurality of beam groupingschemes, each beam grouping scheme comprising a pattern of selectedbeams within each beam group of the configured codebook, wherein eachbeam grouping scheme has a different pattern of selected beams fordifferent first and second quantities of subset beams.
 20. The method ofclaim 19, wherein the selected beams within each beam group areorthogonal to one another.